Hello! btw cant find special help/problem solving forum. So i post here.
Recently, I have been working on my model, and used 2 subdivision levels. So, part of my sculpt was irrecoverably corrupted, and i decided to use trim brush to erase corrupted part. When i tried to do that, i was forced to freeze my subdiv levels. So, i froze subdiv levels, and erased bad part of the model, but when i clicked on freeze button again, all my model became “invalid”(it acquired darker color), except small surface, where i used trim brush.
What have i done! 
The question is, how to make my model enabled again, with returning of subdiv levels ofcourse. HLPHLP!