Yosemite freeze at boot - no safe boot + I/O error

yesterday everything was fine but today my macbook freeze/stuck during the boot. I've done this: - check + repair permission (nothing changed)

- check + repair disk (nothing changed)

- tried safemode (doesn't boot)

- resetting pram with cmd+opt+p+r (nothing changed)

- boot in verbose mode, shift+cmd+v and after "waiting for DSMOS" appear disk0s2: I/O error. (now 6 times, but it will continue I think )

- tried to use fsck in single user mode and it says that the disk is ok - tried to reinstall the OS (nothing changed )

Any idea how to solve it?