The first error here is op admiting he forgot where he kept the seedphrase. If he has ever stored or sent his seedphrase online, either by:
Snapping it saving it on his gallery
Storing on iCloud
anywhere in his device or anywhere at all, the seedphrase could be compromised.
Lesson to newbies, "resist the urge to save your seedphrase online, write it out instead and save in a safe place."
Saving/ backing up wallet seed phrase is very important for ability of accessing the wallet anytime later even if the original wallet and device were broken and no longer are usable.
It's very vital in protection the fund stored in that wallet.
Saving/ backing up a wallet must be done very carefully, properly and there are many steps to do it rightly.
How to back up a seed phrase?Seed Backup Threat Model
Loss due to destruction
Loss due to complexity / not being able to restore from backup
Loss to an attacker
Terrible Backup Schemes
Let's begin by going through some common forms of backing up seed phrases that are incontrovertibly prone to failure.
Storing your (unencrypted) seed phrase in any online service. This includes:
Taking a photo of your seed phrase.
Any note taking apps that get synced to the cloud.
Services that sync files from your phone / laptop to the cloud.