You need to provide a little more info about your circumstances, enough for someone else to try to reproduce it.
Let’s start with saying which camera you are using. Have you tried resetting the camera, which can be found in the camera menus? If your battery fully charged? If your camera in a BBF mode?
What is the shooting mode setting [round dial on top of the body] that you are using? What are you trying to photograph, and do you have enough light? What exposure is the camera reporting, and is the metering system working?
Don’t bother with trying to clean the lens/camera contacts. Unless you can clearly see a foreign substance on the contacts, I would not bother with it. Stains and discoloration do not count as a foreign substance. Leave the cleaning to professionals.
As stated there ja nothing i know to reproduce it like when i said i have not noticed a variable to stop it or to make it, it just happened one day to the other. Yes ive restarted all settings, also restoring to factory settings. Im shooting in M for manuel not sure what bbf is, happens outside or inside at any given moment that is not the variable & yes the metering system should be working, the histogram is even.
Use One Shot mode, not AI Servo. Try to take a photo in Live View mode.
BBF means back button focus. If you do not already know what it means, then it is probably not an issue. It is something that people setup in the camera, and then they forget all about it.
Good advice to try a different lens. Try switching your lens to MF, too.