Photoshop does not let me open files or save then in JPEG

What file format are you trying to open?

• Supported file formats
  https://helpx.adobe.com/photoshop/using/supported-file-formats-photoshop-cs6.html

Are you using File > Export to save your JPGs?

Is your issue with opening the files or saving them as jpegs. If the latter, read on.

Since 22.4, if your file contains items that are not supported in your required format (e.g. layers or 16 bits/channel or hidden pixels etc) then the file format is moved from Save As (Shift+Ctrl+S) to the Save a Copy command (Alt+Ctrl+S). This was driven by changes in the Mac Operating System, although the changes are applied to both Mac and Windows to ensure the two platform versions remain aligned.

https://helpx.adobe.com/photoshop/using/whats-new.html

Dave

Do you have the latest updated photoshop?