Problems with Elements 12

I have a copy of Elements 12 purchase about three years ago. The box has the following numbers on it  PN: 65224798

bar code 5  051254 609520.

I had been working on several images for a number of hours any problems. Some where DNG files and some PSD's. I had been working on a particular PSD which I had opened and closed several times. When I tried to reopen it a box appeared  titled "Sign in required" Please sign in with your adobe ID. The sub title was "Terms and conditions for trial software"

I tried to remove it without success and it is now preventing me opening any files be they DNG, JPEG or PSD's.

It may be worth recording that at the time we had a broadband failure. However as I said above I had been working on the various files without any problems despite the failure and I was aware of the lack of broadband. Broadband has now been reestablished but the problem persist.

I would welcome some ideas or assistance.

David Dennett