I had a phone that was lost the insurance company replaced it so they replaced phone is...

I had a phone that was lost the insurance company replaced it so they replaced phone is now lost but the earlier one that was replaced was found and all I want to do is turn it on to start using it the Boost store person said that the account on the old the First lost one is still active so I have two phones with an active same phone number because it was never turned it off when it was replaced she's telling me I have to wait for a *-month period of time before that number is available or something she doesn't know what she's talking about I'm sure so the phone that is lost it is the one that rings to voicemail looks like notification sounds I just want my phone the one that was lost and found I wanted turned on so I can use it please oh one other thing the lock screen on the phone I can't remember the code so I know I have to probably do a master reset which I thought was the volume key down and the on-and-off button at the same time it doesn't work it just takes a screenshot photo so I need both those issues thank you