Oblivion - How to regain lost skills?

Anyone out there, please help me!

I have been playing Oblivion for quite a while now, but there is something that anoy me very much...

When you have been playing Oblivion for a while you will meet creatures that can "damage your skills"[/color] damage your skills so your skills go down, so you see the numbers of your skills in red color... My question is "How do I regain my lost skills" ?! Is it possible? If not is there any cheat that can do it for me, I dont like to cheat but if there is a cheat that can help me about this then I feel it is very necesery.

I will appreciate any kind of help! Thank you.