I can’t send new emails or reply to emails received.

I can receive and open emails but I can't send new emails or reply to emails received.  I do not get any error messages.  Nothing happens when I click on new or reply. Two of us have hotmail accounts that were changed to outlook.  The only difference I can see is that in the upper right hand corner under my name, the words available and invisible are in background grey, while in the other account, under his name both of the words are in black with a black dot in front of just the word available.