Very frustrated, does anyone know where I can get this slide potentiometer, I found similar on mouser but not with the measurements I need

 

go to the source, at least to identify the full part number
http://www.taiwanalpha.com/en/products/48

better picture would help, including shape of broken lever.
and since product is not made in USA, it would be better to only use metric dimensions.

 

You might look for 10K slide potentiometers on Amazon: This one is very close in size--

https://www.amazon.com/uxcell-Varia...rds=slide+potentiometer&qid=1651599160&sr=8-3

Or check out Alpha matching products at Mouser:

https://www.mouser.com/c/passive-co...ha 10K slide&resistance=10 kOhms&travel=45 mm

 

Please correct me if im wrong but those are 45mm travel distance when my casing is 45mm in length

 

Ill take better pics and use mm

 

based on your drawing travel is 38mm. i do not see such product on the website or any with exact features you hared. but i guess you just need to replace one unit to perform whatever repair. they are simple in construction so it may be worth considering replacing just broken slider on that damaged pot with one from a donor pot.

 

You also have to find out if that slider is linear or logarithmic in how it changes resistance. A simple test is to put the slider at the 1/2 way point as best you can and measure resistance from each end. If it is about the same from each end, it is linear. If the resistance is fairly different, odds are it is logarithmic.
The "B" and the 5L2 portion of the part number suggests linear, but best to measure anyway.

 

here are some better pics, im pretty sure its linear, its from an m-audio keyboard

 

I see red spots at the top end of the slider. Are those illuminated handles? I have seen those, they are quite impressive but not very common.
I also noticed in the photo of the circuit boards, two extra terminals at the bottom. That is why I asked if they were illuminated. That would make the search more challenging.
Have you been able to visit the manufacturers website?
It may be that you will need to repair the broken slide-pot, I hope that you have all of the pieces. Possibly somebody with a 3D printer could produce a replacement for you.