Reinitialize operating system question

Irrespective of the problems you might have with the Mac, best thing to do is to take the easy way. Unless you already did, open system preferences and create a brand new user, then log out from your existing one and get into the new one. Unless it's a system problem this will give you a fresh and untouched user experience and might solve your problem. Reboot your Mac and keep pressed the command+option+P+R keys until you see/hear your mac restarting a second time, then release and let it boot normally..this will reset basic parameters and solve a few potential glitches.

If you don't have install discs you'll need to recover the Os via the net, but most of the times is not necessary to get that far to solve basic problems.