iphone 5c factory reset now has a passcode lock after sitting for a few months

Click here --> If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled

So are you trying to say that the device is also activation locked?

If it's activation locked, and you don't know the credentials for the account used to lock it, you may as well just toss it in the recycle bin. It's useless.