Go to your localbitcoin's wallet transaction history, look for the withdrawal transaction that you did and check its "receiving address".
Open your Electrum and see if that address is in your 'Addresses' tab, ("View->Show Addresses" to enable the tab).
If it's not there, you've sent it somewhere else.
like i put my adress in it but it wasnt my adress. so i lost money cuz of electrum
Sometimes, newbies tend to use another wallet for their "missing transactions".
If you only have one wallet, then it's most likely a clipboard-hijacking malware/virus that changes the address that you've copied or you installed a fake version of Electrum.
(see the other replies to check if you are infected with the malware | verify your downloaded Electrum to see if it's legit)
But neither of those can recover your lost bitcoins, that's to know the culprit.