Please help! mycelium watch only account private keys

[hulla]

He doesn't recall gaining a private key upon the creation of the account, is it possible or does he not know what he is talking about?!

No, that's not possible.

If he generated the private key using mycelium, he definitely was told to back it up. He might have forgotten this. Or he didn't care.
If he imported an address, there was never any private key to start with.

Either way, this is a prime example on how fool proof methods can never be fool proof enough and that for the majority of non-techy people a wallet has to be as simple as using a credit card without any addresses, private keys, transactions, confirmations etc.
Basically for the mainstream user, you'd need to remove every technical aspect of bitcoin. And even then it wouldn't be fool proof enough..

He loaned some cash to a guy and he got paid back with the coins, and he isn't bitcoin savvy, so at this point I'm thinking it's either the guy who paid him back gave him a wrong instruction(whether onpurpose or not) or he accidently deleted the keys and don't remember.

The first mistake your friend did is receiving the money he loaned someone through crypto when he's yet to understand crypto payment because the payment sender may have just scam your friend but to understand the whole issue probably.
1) Whats the relationship between your friend and the person that sent the payment?
2) Is there a chance to get the payment tx ID?

[sk89]

Try to reach out to that guy (who sent the coins) and ask him about the instructions he gave to your friend. It might help to figure out what happened because knowing how the watch-only wallet was created is the key to solve this problem.

You will receive more emails/pms from newbies offering to help you. Do not trust them and ask them to post here if they want to help.

Coins are from a long time ago and he lost contact of the guy:(
Yes as tempting as it sounds I am ignoring all the emails offering help.
Thanks so much for your time and advice!

[bob123]

He loaned some cash to a guy and he got paid back with the coins, and he isn't bitcoin savvy, so at this point I'm thinking it's either the guy who paid him back gave him a wrong instruction(whether onpurpose or not) or he accidently deleted the keys and don't remember.

In this case, it is very well imaginable that your friend got scammed.

If the instructions were to import an address, your friend never was in possession of the coins.
This is a relatively common scamming technique to scam people who are completely new to bitcoin. Usually done via blockchain.com, but works with any other wallet too.