While there are several contenders in this category, I could have recommended all.
Here is one of them; MoboMarket (MoboRobo) . Since you want gratis you could go with the Ads supported version, and it won't cost you a penny:)
Enables you to easily manage multimedia files from your Android or iOS
based devices, back up important data, send SMSs and download new
apps, songs and themes
Usage instructions are also available on the website:
Unfortunately, I didn't use these personally but it is one of the recommended ones on XDA-[PC][Windows] Android Free Universal PC Suites
I did recommend this one because it was one of the free alternatives, (but not implying is best among the given) you can give it a try, and it seems to accomplish what you want. There are far better android manager suites for pc but most of these are paid so I avoided these.