Hi there,
Just starting reusing a small account that was totally inactive. It has 3400 followers, but a reach on posts of 400-600 and 100 views max on stories.
What recommendations can you give me to revive it? Or is it better to start from 0?
Thanks 
You can still use and grow that account.
What you can do is this:
1- start with following users and stories viewing low settings noting crazy, do that for 2-3 days
2- do a few unfollows after that and keep the following and story viewing for another 3-5 days
3 -starting posting, maybe 1-2 post a day max, post some stories as well and like a few other users posts afterward
then you can keep scaling up from there and see the results, you can increase your settings up every 2-3 days and see how it goes