Revitalizing an old site

I have a white hat amazon affiliate site that was doing about 15000 page views a month. Links were all done via outreach/guest posting. The content is pretty good since i wrote it all myself and its a niche i have an interest in..

Due to an accident i was layed up in the hospital for 6 months and stopped working on it. Rankings have since dropped to pretty much nothing.

I was wondering if it would be worth it to try and add new content+do some link building? Has anyone had a similar experience? Is it possible to regain said rankings or would I essentially be starting from scratch?

This depends if there are any spam tags attached to the domain. Check it with algoroo https://algoroo.com/ if there is a correlation of the ranking drop with one or several updates. If not you can regain lost ranking prety easily.

I dont see any penalties in webmaster tools.