user table corrupt

[InnerSelf]

i dont know if this is a common problem but this is my second time. the first time i repaired it with a 2 weeks old backup, but now i didnt back my forum up for at least 4 weeks :s

this is what phpmysql says:

Can't open file: 'user.MYI'. (errno: 145)

Error

SQL-query :

SHOW KEYS FROM `user`

MySQL said:

Can't open file: 'user.MYI'. (errno: 145)

can anyone please help?
thnx!