This guide will walk you through everything you need to know: what language packs are, how to get them safely, step-by-step installation, and how to avoid dangerous third-party sites promising "free verified downloads."
The only to download and install new language packs for modern versions of Photoshop (CC) is through the Adobe Creative Cloud Desktop App . Verified Steps to Download Photoshop Language Packs
If you find yourself stuck in a non-English language and cannot find the settings, there is a known manual workaround to force Photoshop back to English. Adobe Photoshop CS5 Language Pack en_GB | Community