TS-251D - 1 HDD died, getting a replacement

So 1 of internal HDD died and I am getting the warranty replacement tommorow

I recall combining the 2 into a single thin volume, each one is 14.4gb

Meanwhile my Nas rebooted and renamed itself with admin username, lost all my apps

I do have external drives attached to why I have backed up items

if I connect the new one, will it recover my previous stuff?