First of all, restart your computer and see if the issue is fixed or not. If the problem was occurring due to a minor glitch, it will be fixed automatically after restarting your computer. Also, ...

When your Bluetooth mouse suddenly stops working and the entire Bluetooth functionality disappears from your PC, no toggle switch, no Bluetooth in Device Manager, it usually indicates a deeper issue ...

First off, I'm very picky when it comes to mice. I can't stand the Apple-style acceleration curve. Never have, probably never will. I have always used apps like Steermouse to tweak the mice on my macs ...