slave out of sync

[Chris Scheller]

i have replication going between 2 boxes. the master crashed a few days 
ago, and this morning i noticed that the slaves slave thread errored 
out. the binary log and offset had changed on the master and the slave 
couldn't sync up. i got the slave up and running again by changing the 
log file and offset in the slave. but now i am left with out of sync 
data. how do i get these back in sync, and how do i aviod this in the 
future?