not enough detail there to assist in all honesty
is the server running?
what happens if you try to run the command line client?
what happens if you try to run say thge MySQL GUI tools?
what error message are you getting?
what front end tools do you have?
are you trying to develop SQL or an application, if application what front end language are you using? PHP, ASP,
VB Delphi?
is it a problem with the server or is it a problem talking to the server
is it a permissions problem, have you GRANTed appropriate permissions for your user(s) to the db's you are using