Wallet

Hi - in 2014 i was buying and selling a few bitcoins with a friend (he was the bitcoin guru) - i initially downloaded the bitcoin core and was buying 0.25 up to 1.0 evry few weeks mainly from Coinduit and i have my key and wallet.dat file stored offline. We were also using locabitcoins...to cut a long story short the lad moved away (passed away) and my interest became a bit stale - i put electrum locally on my laptop....opening electrum it states watching only wallet and i dont recall ever creating a seed or passphrase as i think i just imported address and had just done a back up of wallet.dat in coinduit folder which i have on a data stick and written down in a notebook. I know i have a balance of at least 1 BTC but as i haven't been active with BTC online or some time i am having a brainstorm. Am i now stuck with not being able to sell or retrieve my BTC? Thanks in advance