Does the games folder contain default games only or it has games downloaded later too? Try opening after removing the mem card. If it opens then Scan ur memory card for viruses with a good antivirus. Take a back up of ur card data. Then format it. & restore the back up.
If it doesn't open even after that then Restore factory settings- all from the settings menu. But do remember to make a data back up of ur phone before u do it. Even that doesn't work then u'll have to hard reset the Phone using the ovi/pc suite or contact authorised Nokia care.
Pls mark the post as solution if it solves your problem.