Do you have your 24 words (that were given to you when you first turned your Ledger on) written down?
If that is the case, then you have nothing to worry about when resetting your wallet, as all of your addresses are generated from that (you might need to create a new LTC account afterwards, though).
Yes I do have my 24 word seed written down.

It's highly unlikely that you'll need to reset it, though.
Are you sure that you're using the correct BTC account (there can be multiple accounts with multiple addresses generated from them, all from a single seed)?
I don't really understand this, sorry?. I'm pretty sure I'm using my only one BTC account.
Does the address ever show up in your wallet right now?
No, like I mentioned before - the BTC address my Ledger gave me does not show up anymore when I check the addresses.

Also, it's possible that you're using the old Litecoin address format (do your Litecoin addresses start with an M or a 3?).
I don't think so as all the Segwit LTC addresses begin with an 'M' and Legacy ones with an 'L' - I used Segwit so my LTC address begins with M
If you have sent Bitcoin to a Litecoin SegWit address, it's still possible to recover that (although rather quirky).
Any other suggestions?
Surely someone must of had this same issue as me and managed to recovered them?