For a great explanation on seed phrases and wallets, check out our article explaining how blockchains, wallets, and transactions work.
Lost Seed Phrase
As noted throughout Helium documentation, losing your 12/24 words means you will lose your only access to your hotspot and HNT balance. Unfortunately, neither Bobcat or Helium can help retrieve lost seed phrases.
Incorrect Seed Phrase
When entering an incorrect seed phrase, you may be logged into a wrong wallet or may not be able to log in at all. When typing on mobile devices, keyboards often add an extra space at the end of words as part of predictive text, or will change words to other words as part of predictive text. When typing in your seed phrase, be sure to double check each word after it is entered to be sure it matches what you have recorded.
Protecting Your Seed Phrase
A great option to protect your seed phrase is to use a cryptocurrency hardware wallet (sometimes known as cold storage). This will work to secure your funds however at the moment, you are not able to secure hotspot ownership using a hardware wallet. For more information, see this article.
Other common options for backing up seed phrases are to write them down using pen and paper and store them in a secure location, or use one of many metal seed phrase backup solutions which can withstand fire and other environmental hazards.
Regardless of how you back up your seed phrase, never share your private key/seed phrase with anyone else! Anyone who gains access to your private key/seed phrase has control over all funds and items (NFTs, hotspots) belonging to your wallet and can do with them as they wish. Be sure to never lose your seed phrase or you will permanently lose access to everything contained in your wallet!