cannot post / update or upload media

Please can someone help me. I manage the website for a sports club and I have been using wordpress on my lenovo laptop on windows 10 on firefox for quite a while and it has worked fine. Today I can access the dashboard, stats, etc but when I try to post, update a post or upload media it hangs for ages and then I get the following:

if I am trying to post or update a post I get a new page with –
“The connection was reset
The connection to the server was reset while the page was loading.
The site could be temporarily unavailable or too busy. Try again in a few moments.
If you are unable to load any pages, check your computer’s network connection.
If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.”

if I am trying to upload media I get a little white box with: “HTTP error.”

It seems like it is a problem with the connection to the server – could it be timing out? I can deactivate one plug in, for example, but if I try to deactivate them all at once I get the ‘connection reset’ page as above.

I spoke to someone at godaddy who said it was something to do with my end. I have tried doing the above on another computer and it works so it is definietly something to do with this pc. The same thing happens on different browsers on this pc (including private browsers).

Does anyone have any ideas what it could be as I really need to work from this laptop as all the photos, etc are on it?

Oh, and since I started trying to sort this I have also lost the wording when I go to edit a post. Everything is still on the site, just not appearing when I click to edit it. I don’t know whether this is connected or is from something I have done today.

I am a novice at this so please bear with me if this is a really simple problem but the chap at godaddy couldn’t explain to me why it might work on one computer and not another.