Wow now I progressed further with the game, i found that i really like the game till I went into the elven tomb, when i fought wights wich i used neg plane prot i noticed my cleric lost a lvl then i came to a horrified conculsion and that the vampire i fought before had drained some lvls from my party but since i saved that file i lost it forever, or is a way to get lvls back?

You cannot restore drained levels. You can just continue playing and get new xp to level up again or load an old save.

oh well dont think the game uses all the adnd rules because i dont see attack, only health and spells

Well, the second game is easy because you can just Jump over the wall that is supposed to kill you if you try to escape the desert.

(Of course, my understanding is that doing this causes you to skip nearly the entire game, so if you actually want to experience the game, you might want to play through without abusing this major skip.)

But since you can i,port your dafe i want to beat strahs possesion first