will I lose my contacts?

Not if you do a reset, however if you do a restore, which is the only troubleshooting step you can do that has the word factory in it, you will lose everything. That wipes the device and takes it back to factory specs.

You take the time to make a backup of the device before doing this factory restore. You also make sure you have your contacts synced somewhere else, such as Outlook, an email account, or a cloud service, such as iCloud or other cloud provider.