Broken handle on window - can I DIY this?

[Petal]

I've got aluminium windows, and the bathroom window has a small top hung window. Unfortunately, the black handle has broken off, so the window can't be closed now. I was wondering can I repair this myself, can I get these handles somewhere or do I need to get a window repair company?

 

[NHG]

Firstly is the handle screwed in or pop-rivited in. If screwed in its a diy job if pop-rivited its a job for the window repair men/women

 

[Petal]

It is rivited and I have repair guy in as we speak as I figures afer looking at it carefully that I wasn't going to be able to do it as don't have the right tools for it....