Our master bathroom's window has a crank attached to the window frame. The window is in good shape and the frame is too. My situation is that the crank doesn't operate the window to open or close.
Also, the surrounding area where the window is set is cold, like maybe the insulation is weak
All of what said I'm thinking a major operation of professional doing the job for me could I be right, I felt that once I open the crank window I would have access to the crank and its screws, and this would give an opportunity to remove the crank. But if te window crank cavity is worn out, I'd be up a creek for having opened up a pandora's box.
It sounds like you've found yourself in the unfortunate situation where a window's hardware has worn out faster than the window itself. I can relate: A few years back, I had the same issue with my bathroom window. I went as far as caulking it shut until I got around to it, so it wouldn't get stuck in an open position! A few months later, I replaced the window altogether.
Do you know what brand of windows you have? If you do, attempt to get a hold of replacement hardware for the crank. If not, you'll probably have to replace the entire window. Here's some silver lining if you find yourself in that second scenario: All replacement windows are custom-made by their very nature - that is, designed to fit the size of a specific opening - and might not be as expensive as you'd expect. Good luck!