I was accidentally move ''/usr'' directory to ''/home/sagor/Download'' that time my pc screen become black . And later with live session I manage to put the ''/usr'' directory to its original position. Then my pc was ok boot up and I got everthing back like before. But when I try to run a softewre its give error.
After some research I found that all softwere lost its permisssion.
Is there any way to put the orginal permission back ????
NT: Can't reinstall, I have dual boot ubuntu with windows 10