EF 70-200mm 1:2.8 L auto focus not working.

[Reynolds1823]

Hey Everyone. I have a 70-200mm 1:2.8 L lens that I am shooting on a Canon EOS 90D. My auto focus worked until yesterday. The lens keep going in and out as if the subject was too close and out of the focal range but it never focuses. Manual focus is working fine. I have tried in all modes and focus modes. My 24mm is focusing on the body so I've narrowed it down to the lens. Thanks for any help! 

[jrhoffman75]

If you select a high contrast subject about 10 feet away and the lens won’t focus but a different lens will it is likely a lens problem.

what version is the lens.

[Waddizzle]

Blow out the mirror box with a rocket blower. You could have dust on the AF sensor. Double check your lens switch settings. 
I know you said you tested in all shooting modes.  But have you tested it in the default green [A+] mode?