Cannot access Network Admin getting logged out, cannot get back in

You will tell from this post that I fall into the “don’t know what you are doing categories” I am trying to learn.

I have read lots of posts and I may know what may be the problem but I can’t get to my network admin general settings screen to fix it.

As of yesterday everytime I try to access the “My Site” Dashboard and either amend a plugin or just do anything – I am logged out. The log in screen asks to prove my humanity and I cannot re-enter the site.

I can re-enter my website however if I refresh the page and log in via the normal log in box without the humanity checker.

I believe that in the general tab on my site option that something may have happened regarding my url but I can’t log in to access the tab and carry out this instruction

“In wordpress settings > general menu I had my “site address (URL)” set to “www.domain.com” when I switched it back to just “domain.com” that worked for me.”

I am no coder – I do know where the file manager is on my server’s site and yesterday I did do something to the .htaccess file which I hope today I have put back to what it looked like yesterday.

As someone who is a bit of dunce when it comes to this can anyone guide me either via the server to correct this problem and help me regain access to the network admin.

PS I have flushed cache, reinstalled browers, changed passwords, deactivated the last plug in via the back office.