avast programme has been stopped

The message on screen reads- Avast antivirous programme has been stopped or is in an inconsistant state.Please restart.Nothing happens when i click restart.What do i need to do?

You don’t say what avast version you are using (avast free/pro/ais, avast 7 or 8 ) ?
What is your operating system ?

Try a repair of avast:
XP - Add Remove programs, select ‘avast! Anti-Virus,’ click the Change/Remove button and select Repair, click next and follow.

Vista, win7 - Control Panel, Programs & Features, uninstall a program, select ‘avast! Anti-Virus,’ click the Uninstall/Change and select Repair, click next and follow.

You may need to reboot after the repair.