Can't use my Photoshop CS2 after Windows reset [CS2 is dead]

Even if you had an installer, you can't activate it.  After 15 years, it's time to get new software.

As @John T Smith  said, Photoshop Elements is affordable and a major step up from what you've been using.

Another option would be the deeply discounted Photography Plan bundle for USD $10/month x 12 months.  Everything a digital photographer needs and more:
-- Photoshop CC and Photoshop for iPad
-- Lightroom on desktop, mobile and the web
-- Lightroom Classic
-- Free Portfolio website + hosting
-- Spark with premium features
-- Bridge
-- 20 GB cloud storage (upgradable to 1 TB).
https://www.adobe.com/creativecloud/photography.html

Photoshop Elements http://www.adobe.com/products/elements-family.html is a one time fee

CS3 and earlier are completely DEAD programs due to the activation server being retired