My yahoo is blocked on all pc.s what do i do...it

If you are able to sign in on the website and you can access your email box. It is clear that your account is fine. If you are unable to sign in on the mail website and it gives the same error. Then just wait for 24 hours, it will be unlocked. It is not your fault some time people try to break in to your account and account is locked due to security reasons.