There is no way to recover a lost seed
It is impossible to access the coins without the correct privatekey or seed. If you are not sure where you backed up your seed, then your best chance is to keep trying to locate the saved seed.
Note! It is possible you wrote the seed with extra spaces or you made other small mistake. Also pasting from "smart" text editors may change the text format, even though it would look identical.
Warning! Capital letters also have an effect on your wallet seed so make sure you check your Caps