I've been having trouble for a few weeks now in signing in to my main Microsoft user account.

This is causing all kinds of problems when using my computer.
1) I can no longer send/receive email on this account via either Thunderbird, my email client, or via the Hotmail website. When I try to sign in to the website, I get a nearly empty page that says:
Microsoft Account
We can't show you that page

Our server is having a problem. We're working to fix it as soon as we can, so try again in a few minutes.

It's been like that for weeks now so clearly it is NOT a short-term server problem.

2) When I try to play various Xbox games on my computer - I'm running Windows 8.1 on my laptop - it asks me to verify myself through the account but I'm unable to sign in to complete the verification.

3) When I try to install a new program from the Store, it wants me to sign in and I can't, making it impossible to install programs.

I suspect the heart of the the problem is that the account was originally issued to me via my old ISP. When I moved house at the end of August, I wasn't sure what would happen to the email account and the ISP's tech support contradicted itself when I tried to ask. I was pleasantly surprised to find that the account kept working fine until a few weeks ago; I had originally expected to lose access to it about 30 days after I cancelled my service. I thought perhaps the fact that it was also a Microsoft account was somehow keeping it alive.

I've long since moved on to another ISP but I contacted the old ISP about this issue and they were, as usual, vague and self-contradictory.

If the email account is dead, I can live with that but I'd like to be sure that there isn't something I can do to reactivate it before I give up on it.

Also, I would really like to know what to do on my laptop if I want to keep the user account associated with that email address. I've got a bad feeling that you're going to tell me to write off that user account and set up a new one based on some other Microsoft account but maybe I'm just being unduly pessimistic. I have this account configured the way I want it on my laptop with all the apps I currently need, including games with decent accumulations of scores, like gold medals in various of the XBox games. If I must abandon this user account, is there some fairly painless way to copy all the various apps, settings, scores, bookmarks, etc. over to a new account or am I going to have to create new IDs for the various games and begin whole new IDs and scoring histories?

Ultimately, I HAVE to be able to install new programs (or reinstall old ones when they start misbehaving). Is there any way to be accomplish that with the current problematic email address/user account?