Office 365 no internet connection

Hi

I recently installed a new Sky hub which has caused endless problems.  Today I had to type an important letter for the Solicitor I work for but when I tried to attach it to an email to him I could not find it in my document files. I opened Office 365 and it was there. When I clicked on the letter a message popped up that I was not connected to the internet which was rubbish as I had accessed my emails. I have reinstalled Office 365 but still cannot find my file. Please please help me I have to get this email off urgently. Could you reply by return.