whirlpool s/s refrig. not cooling

frig. has been making a clicking noise coming from the back bottom of the
frig. for several months but has been working fine until several days ago
when just quit cooling, both sides. unplugged frig. then plugged back
in. worked for about a day then quit cooling again. research pointed to
the start/overload relay. i kept unplugging and plugging back in until i got
relay. day before i got relay heard a humming/buzzing noise from back of
frig. went ahead and unplugged frig until i got relay and installed. lites work ,fans running but not cooling. compressor seems like its humming but
not like it would normally . not cooling at all. is there anything else that
could possibly be causing this or is compressor bad, if so is there any thing i can do to salvage compressor. used factory relay just like relay removed. could the capasitor possibly be causing this . any help would be
appreciated. thanks