no , when I load it up on blockchain.info it says "Transaction not found"
If I update it will I get my BTC back or is that gone now ?
Backup your wallet files first.
Your coins will not be lost. The problem here is that your client is sending transaction that has high-s value and the network has stopped accepting them. Multibit Classic v5.17 fixed this issue and enforces the low-s value in transaction. Your transaction would then be able to get propagated and confirmed.
Check your fees, just in case.
Reset the blockchain once you have done upgrading.