Hi @RadhikaS 

Essentially, you can view the workflow instance table, in each Nintex content DB, and that will give you the name of the workflow, and the history list it's associated with.

If you want to combine that into a powershell, and to check all the Nintex content DBs, then you could modify the PS script here: https://community.nintex.com/t5/Community-blogs/Finding-all-of-the-workflows-in-your-farm-using-PowerShell/ba-p/82561

It just needs the column for the SQL column historylist added to it.

I hope that helps,

Sumit