Mnemonic Seed phrases are made up of 13 or 25 random words.
The 13th word is a repeat of one of the other 12 words.
Simply type in 12 combinations, trying each word until you find the right one.
But if you have somehow have misplaced the entire mnemonic seed, this is not something we can provide to you.
We do not have access to your mnemonic seed for privacy reasons.
Make sure to keep it stored safely off of your device.