For the truly tech-savvy, a hex editor like HxD can be used for manual repair, which is what the "Patch" mode of the toolkit automates.

If you aren't ready to buy a license, there are several reputable free tools and methods you can try first: Bitwar Video/Image Repair:

Searching for "new" or leaked license keys on third-party repositories exposes your computer and data to several critical vulnerabilities. 1. Malware and Trojan Delivery

What (camera, phone, SD card) were the photos taken on? How many files are currently corrupted?

The JPEG Repair Toolkit offers numerous benefits to users, including:

What (Windows or Mac) are you currently using? Approximately how many files need to be repaired?