if you install mysql under windows system, sometime it will suddenly unable to start the service,
i face this issue quite a few times already, finally i found a solution for it,
1st step check the error, under your installation path for mysql, check the data/mysql.err, it the error showing you something like this ..
050213 20:43:37 InnoDB: Starting shutdown…
050213 20:43:40 InnoDB: Shutdown completed; log sequence number 0 1051715
050213 20:43:40 [Note] C:\Web\mysql\bin\mysqld-nt: Shutdown complete
this should be the log file having problem!
2nd step remove the ib_logfile0 or ib_logfile1 in the same folder
3rd step restart the mysql…
da da da… mysql service is running again
p/s: i'd got the same problem and i tried the tips ahead, its works for me..try and error would give you experience...hope this will help... XD