I just bought a new HDD for my pc yesterday,so I decided to reinstall backtrack 4 into my system as i wanted to indulge myself in security and pen testing,right after I installed it,I try to connect to the internet using a few steps mention below:

Code:
1. /etc/init.d/networking start
2. ifconfig wlan0 up
3. iwconfig wlan0 mode managed essid "my ESSID"
4. iwconfig wlan0 ap "myap"
5. iwconfig  wlan0key "my WEP key"
6. dhclient wlan0
It was working fine and I was able to connect to the internet,and just like anyone,i start an update:

Code:
 apt-get update
apt-get upgrade
after the upgrade,I shut down my pc,but later on when I try to boot up the backtrack,I can't seems to connect to the internet by using the method mention above.This is the error i encountered:

Code:
~# ifconfig wlan0 up
SIOCSIFFLAGS: No such file or directory
Code:
~# iwlist scanning
lo        Interface doesn't support scanning.

eth0      Interface doesn't support scanning.

wmaster0  Interface doesn't support scanning.

wlan0     Interface doesn't support scanning : Network is down
Code:
~# iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

wmaster0  no wireless extensions.

wlan0     IEEE 802.11bg  ESSID:""
          Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated
          Tx-Power=0 dBm
          Retry min limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0
I've been lingering around this problem on and on,google for info for couple of hours,and try to modprobe -r rt73usb and rt2500usb,but still no luck,below I think is some info useful for you guys to help me up.

Code:
~# lsmod

Module                  Size  Used by
ipv6                  239348  14
sbs                    10940  0
video                  18024  0
output                  2388  1 video
sbshc                   4500  1 sbs
acpi_cpufreq            7808  0
cpufreq_ondemand        7080  2
cpufreq_powersave       1268  0
cpufreq_stats           4728  0
cpufreq_performance     1300  0
cpufreq_conservative     7048  0
freq_table              3476  3 acpi_cpufreq,cpufreq_ondemand,cpufreq_stats
iptable_filter          2324  0
ip_tables              10916  1 iptable_filter
x_tables               13592  1 ip_tables
parport_pc             24292  0
lp                      9412  0
parport                30572  2 parport_pc,lp
arc4                    1588  2
ecb                     2484  2
snd_hda_codec_realtek   194936  1
rt73usb                26104  0
rt2500usb              21112  0
rt2x00usb               9684  2 rt73usb,rt2500usb
rt2x00lib              36436  3 rt73usb,rt2500usb,rt2x00usb
led_class               3608  1 rt2x00lib
snd_hda_intel          24712  3
snd_hda_codec          57204  2 snd_hda_codec_realtek,snd_hda_intel
input_polldev           3132  1 rt2x00lib
mac80211              204728  2 rt2x00usb,rt2x00lib
snd_hwdep               6776  1 snd_hda_codec
snd_pcm_oss            37728  0
snd_mixer_oss          14324  1 snd_pcm_oss
snd_pcm                67704  4 snd_hda_intel,snd_hda_codec,snd_pcm_oss
snd_seq_dummy           2424  0
psmouse                41732  0
serio_raw               5016  0
cfg80211               61268  2 rt2x00lib,mac80211
snd_seq_oss            27328  0
snd_seq_midi            5952  0
snd_rawmidi            19488  1 snd_seq_midi
snd_seq_midi_event      5972  2 snd_seq_oss,snd_seq_midi
snd_seq                47568  6 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_timer              19068  3 snd_pcm,snd_seq
snd_seq_device          6048  5 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq
rtc_cmos               10156  0
rtc_core               15792  1 rtc_cmos
rtc_lib                 2388  1 rtc_core
shpchp                 31560  0
snd                    50468  16 snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_seq_oss,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
soundcore               5856  1 snd
wmi                     5960  0
snd_page_alloc          7836  2 snd_hda_intel,snd_pcm
i2c_nforce2             6648  0
evdev                   9120  8
sg                     25064  0
firewire_ohci          22648  0
firewire_core          40640  1 firewire_ohci
forcedeth              55136  0
ata_generic             4536  0
pata_amd               10744  0
pata_acpi               3892  0
fuse                   53104  7
Code:
~# lsusb
Bus 002 Device 003: ID 046d:c054 Logitech, Inc.
Bus 002 Device 004: ID 04ca:002f Lite-On Technology Corp.
Bus 002 Device 002: ID 058f:9360 Alcor Micro Corp. 8-in-1 Media Card Reader
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 148f:2573 Ralink Technology, Corp. RT2501USB Wireless Adapter
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
If there's any other additional info that is needed by anyone,feel free to tell me,hope any expert could lend me a hand,thanks!