My sims 2 game wont start up anymore

Hello,
Can you help me?
My sims2 game wont start up anymore, my computer wont even read the disc. Normally it does an auto start but now it wont. When I click the icon it says please insert the correct cd-rom select ok and restart application even though i have the right cd in. I have tried cleaning the cd but i dont knoow what else to do. can anyone help? Thanks in advance