Check the fuse
I have the same problem on my 95 Sable LTS
how much would it cost on a 2004 mercury sable
There is no fixing a broken motor mount. Replace them with a new ones.
Fix the drive belt.
You will have to take it apart to determine why it's not working then you can fix it.
Physical damage to a cylinder is seldom repaired. More often the motor is replaced.
Maybe the belt tension is too tight. This very same thing happen to me on a 92 Jeep Cherokee. Is the belt the right belt ? Length , width and design Check your routing If you did not move any components ( fly wheel ???? ) then look at the belt. looks like you got to change the belt again anyway get a belt from a dealership
These parts are only fixed by replacement.
Chain and it is a very (~1000.00) costly fix.
Your local auto parts store can help you with that.