Yes, this is one of the best ways of making sure that an update is as good as it can be on your phone. Or just sorting out various issues.
But I don’t want to lose all my phone contacts!
Done right you will not lose a single contact. I recommend that you use Google for all your contacts.
If you don’t got your phone setup that way, you can easy do it in People > 3 dot menu > Manage contacts > Copy contacts, where it will ask from where to copy and then to where.
I don’t want to lose my messages!
Done a guide on that before, it’s very similar in Lollipop as described in that.
And, you of course got HTC backup and other ways. I tend to keep as little as possible on my phones, just making sure that contacts etc are safe.
You’ve got two ways in doing a Factory reset.
Open Settings > Backup & reset > Reset phone, will warn you about what it will remove. And, on the bottom part of it you have a tickbox for Erase SD card, which you of course might want to avoid if you want to keep the content on the card.
Via hardware buttons on phone
- Power off phone
- Press and hold Vol down , press power button until you see bootloader (3 happy androids on skateboards at bottom of page). Release vol down.
- Select Factory reset, and just go with it.
And a third way that I almost forgot about
When wiping the cache partition, there’s an option for factory reset there as well.