Today, as usual, I was writing my notes here ion LangCorrect, but this time I was using my phone.

Forom some kind of mistake, I losedt all my progress just when intendedI was about to upload my writing.

Due to = from
Past tense of "lose" is always "lost"

What anI was so angry!

You can't say "what an angry," but you can describe yourself as angry.
If you want to complain about the situation instead, we'd usually say (vulgar) "What bullshit!"

I was just about to thrown my phone out of the window, when it suddently rianged.

Past tense of "ring" is always "rang"

I wasn't expecting any call.

Alternative: I wasn't expecting any calls.

It was my friends.

This means you had multiple friends on the phone call.

The first thing I did when I joinanswered iwas to thanks them for being so opportunecalling at the perfect moment, and I explained my experience.

More natural

Our meetingcall lasted about 2 hours, t. They are funny and improved drastically improved my mod.

A meeting is typically in person or over video call and is for business/professional reasons.

They are funny = they are always funny
They were funny = specifically, they were funny during your phone call

I'm writing this late atin the evening, with the energy I have left.