Can’t create new, edit, or send emails in Hotmail account

Last night, I lost the ability to create new e-mails, edit existing drafts, and forward e-mails in one of my Hotmail accounts. 

The problem started while I was typing a message - I clicked on "Save Draft" and the text suddenly disappeared.  I went into the drafts folder and found the email I had been working on was there. I opened the file, but when I clicked the button to continue editing it, nothing happened.  When I clicked on "New" to create another e-mail, nothing happened there either. 

Here are some other notes:

• Even though I can't generate emails, I am able to receive and open them.

• I am not having any problems with my secondary Hotmail account; it is just with my primary one. My husband and daughter have no issues logging into their Hotmail accounts.
  

• The issue is only on my PC; there are no problems creating, editing, or forwarding when I access the account on my Android tablet. 
  

• The problem exists whether I log in via Firefox and Internet Explorer. 
  

• I cleared Firefox & Explorer histories. I did a disk clean-up. I deleted all Internet logs.

• There were no updates installed on my computer for several weeks prior to the problem arising.

• I did install the dozens of updates that showed up last night (about 3 hours after the problems started), then shut the computer down completely. I was hoping that one of those updates would magically fix the problem. Unfortunately, when I turned the computer back on this morning, the problem(s) still exist.

Does anyone have any ideas what happened to this particular email account and how to fix the problem?