My PC will not play my cd disc

What kind of discs are they? Are they commercial music CDs or are they ones that you've burned?

Commercial

What happens after you pop the discs into the computer? Any error messages or dialog boxes?

Can the CD/DVD player play any discs?

Have you tried using a good CD/DVD player cleaner disc?

You need to find out if other CD's can be read, to narrow out whether the ROM can read/write. It's a possibility it could be: Brand of disk, ROM read/write head, loose cable (can still have power data cable was loose), faulty device, bad driver. Put a music CD in and see if the CD plays at all, if not, bad ROM, if it does play then the write head could be damaged or no longer working. If these are the same CD's you have used before, then invest into another CD/RW ROM they are only $30 or less, if it is a Laptop, it might cost a bit more but still just as easy to install, seek further help from your manufacturers manual for ROM installation on a laptop.