By wearing a walking cast for broken ankle could i work?

Depends: That would depend on the type of work you do. If your work involves a lot of walking or climbing, you might want to request an alternate duty temporarily; if you're walking only occasionally, there shouldn't be any problem. Just don't be in a hurry and be careful with steps and wet/snowy/icy walkways.

Depends: If you have a desk job that does not require you to be on your feet all day.

Depends: On the type of work you do. If you have an office type job that allows you to sit you can probably work.