if u r
ABSOLUTELY sure dat d pw u r entering is correct den check ur caps lock 2 c if it is eanbled or disabled and do d opposite while entring d pw nxt time
it could very well b possible the sum 1 may have checked out your account even without havin 2 enter ur pw
u could have checked d
Remeber me on this computer box while loggin in
so d next person using dat computer and accessin Yahoo! cud easily have gotten access 2 ur account
P.S: b4 u jump 2 extreme conclusions i suggest dat u check out d
Sign-in Problems page 2 c if u can either get back ur old pw or r allwoed 2 change it