SR SUNTOUR Fork Axle 15QLC32-110 Plus Suntour
These things work great... if you know how they work and people often destroy them if they aren't familiar with how they operate. If you destroyed yours, learn how they work, then buy a new one.
This is for a Boost Fork - meaning the axle is 15mm in diameter and 110mm wide (inside of dropout to inside dropout on other side).
Flip the lever, push in the other end, push axle through.