[Help] updating firefox to latest

[Natty Dreed]

hello every one,

I just runied my firefox by updating it to 3.5.7

i search in the forum for updating and i got this script

echo Type only the version number i.e. 3.0.10
 read VER
 tar -jxvf firefox-"$VER".tar.bz2
 rm firefox-"$VER".tar.bz2
 rm -r /usr/lib/firefox-3*
 mv firefox /usr/lib/firefox-$VER
 rm /usr/bin/firefox
 cp /usr/lib/firefox-$VER/firefox /usr/bin/firefox
 cat /usr/bin/firefox | sed "s|moz_libdir=/usr/local/lib/firefox-"$VER"|moz_libdir=/usr/lib/firefox-"$VER"|g" > /usr/bin/firefox1
 rm /usr/bin/firefox
 mv /usr/bin/firefox1 /usr/bin/firefox
 rm /usr/bin/firefox-3.0
 chmod 755 /usr/bin/firefox

after that firefox not running any more

if there any way i can downgrade to the old verison

[Natty Dreed]

update:

I follow the instruction in this url and i got it Done right away