I'll look past this being the wrong section for this post since english isn't your first language, but I cannot understate the importance of NOT trying to fix that unit. Repair cost will exceed the cost of a new unit and isn't worth the effort.
Sorry, but you are better off buying new/used gear that is still in working order. Also, don't get hung up on buying a new HTIB (home theater in a box) because you are always going to get better quality with a system you put together yourself. It doesn't have to be expensive either.