..... Is there a way to get in touch with it again without resetting the phone?
If not, can I retrieve my data before hard resetting?
You might want to try re-flashing your S7 with its stock ROM. While a custom, third-party ROM requires you to root your phone and install a custom Recovery, a stock ROM does not. Also, keep in mind a Factory Reset is a bit of a misnomer as all it does is wipe the /data partition (a general access partition dedicated to just your personal data and things). A Reset does NOT affect the partitions where the Android operating system resides, so it will not fix an operating system problem (well, if that is the problem you're having with your phone). The operating system is the same before and after a Factory Reset, it's just a matter where the /data partition is cleared. Using the Odin utility, you can flash the stock ROM, and unless there's a problem, the /data partition should be left as is. Here's a guide that walks you through the process:
How To Flash / Install A Stock Firmware Using Odin Tool
(Just a side note, it's important you do
NOT enable the 'Re-Partition' option in Odin. That will wipe your /data partition.)
There are links in the article pointing to the different items you need to download first but just to add:
-- the biggest download will be the stock ROM, I recommend using sammobile or updato. Both are reliable sources for Samsung stock ROMs. (sammobile intentionally restricts its download servers bandwidth so even you have a fast connection on your end don't be surprised if it takes quite a while.) Be absolutely sure to use the specific ROM for your S7 model, don't substitute a 'similar' model, ROMs are not interchangeable.
sammobile
https://www.sammobile.com/firmwares/search/galaxy s7/
updato
Download Firmware – Samsung Update
-- If you encounter a problem using Odin, try a different version. It has limited backwards or forwards compatibility so use the recommended version for the version of Android you're working with.
Download Odin (All Versions) for Samsung Galaxy Devices
Also, if you have Samsung Kies installed on your PC, uninstall it or at least be sure it's not running in the background, some report an issue where Kies and Odin conflict with each other.
-- If you don't have access to a Windows PC (Odin is a Windows utility), there are some options. There's an Open Source alternative called 'Heimdall' that's available for Linux, Mac, and Windows.:
http://glassechidna.com.au/heimdall/
There's also a Java based alternative, Jdoin3. Never used it but if you do please post your results on how well it works out for you:
[Steps] Download & Install Odin (Jdoin3) For MAC OSX