Scroller is not working

I do not know how long you have had this, but if it has been a few years and the scroll wheel is smooth, it is just because of wear and tear, and the easiest way is to buy a new mouse.

I had a similar problem with a different brand of mouse. The axle on the scroll wheel had broken due to excessive stress, so I took the thing apart and used some super glue to stick it back on. Surprisingly enough, it's still holding up, so you might want to try this before you go and buy a new mouse. You have to be careful and make sure the axle is aligned to the spot it broke off from and that it's not crooked, or otherwise the wheel could "wobble".

It's almost always a cracked wheel or the mechanical encoder is broken. Buy a new mouse, they're $10-15 a pop for a basic no frills mouse like the Logitech M100 and many, many private label ones which are often under $10. A mouse is a mouse, as long as it's not a Magic Mouse it will work and is probably ergonomic enough.

I have a nice mechanical keyboard, and yet I still buy $8-20 throwaway mice. I throw more money away on eBay and yard sales then I will spend on a basic mouse (or a spare I got on clearance). if you want to try and see what you can do, take it apart and see but most of the time the mouse is a lost cause. You can get them for $8 at Walmart: https://www.walmart.com/ip/onn-3-Buttons...