For no reason my laptop switched my user account from admin to standard. It's my only user account so now it's in a mode where I can't switch it back to admin. What should I do?
You can't switch the account back while using the account - that would be a security hole.
You will need to use another administrator account and use that to reset your user account.
Login as "Administrator" (the built in account) and do it from there.
However, as Matt points out:
and as Moab points out you can't boot into Safe mode and sort out the accounts from there.
Do you have another administrator account that you could use?
Once you've done that it would be worth investigating why your user account got switched - assuming you (or someone else) didn't do it.
Just create another admin account. And then use it to upgrade your old account.
There is a reason why the default Admin is disabled. It is a potential security. It's ID and name is well known and unchanged from system to system.
I don't see the point of all these "tips" that will enable the account. It doesn't do anything that any other Admin account can't do. Enabling it just increases the attack surface of your machine and opens a vulnerability that you don't need. Even worse, some machines have their local security policy set so the built-in Administrator account has auto approve UAC controls. It just sounds like a vulnerability that you don't need.