YOU SAID:
he told he couldn't come to the party tonight
INTO JAPANESE
彼は今夜パーティーに来ることができないと言った
BACK INTO ENGLISH
He said he couldn't come to the party tonight
INTO JAPANESE
彼は今夜パーティーに来ることができなかったと言った
BACK INTO ENGLISH
He said he couldn't come to the party tonight
You've done this before, haven't you.