Hi Vanessa,
You should be able to reinstall it using your Windows CD.
If you step through the following:
1. Click on Start
2. Click on Settings (95, 98, Me, 2000) skip if using XP
3. Click on Control Panel
4. Click on Add\Remove Programs
5. Click on Add\Remove Windows Components (XP, can't
remember for other OS's)
6. Look for Accessories and Utilities (XP can't remember
the name in other OS's)
7. Click Details
8. Look through the list for Paint and put a tick in it
if it doesn't have one. If it does, then you will have to
take the tick out, click on OK twice and then reboot.
Once the restart has finished then step through to that
point and put the tick back in. This should replace the
missing file.
Cheers,
Frankie.