SysInspire 7z password recovery software is a helpful tool for recover long combination password using three wonderful methods brute force attack, mask attack, and dictionary attack. You can use the free trial version to recover the first three characters. It is supported by all Windows versions - 10 (32-bit, & 64-bit), Win 8.1, Win 8, Win 7, Win XP, & Win Vista.

More info: https://www.sysinspire.com/blog/unlock-7zip-password/