When I update my iPhone 4 sim does not support??help me.....

Sounds like your iPhone was hacked/modified/jailbroken to work

with wireless carrier other than the one it was purchased from. The

update has relocked it to the original carrier. Contact the original

carrier to see if they offer unlocking and if you qualify - only the

carrier to which the iPhone is locked can unlock it.

What does it say when you look at Settings=>General=>Carrier?

Be advised that the previous modifications to change from original carrier

to your local Carrier may have rendered the software unable to be

officially unlocked.

Try removing the sim, cleaning the contacts and re-installing. Get new

sim from your wireless provider.