First, check the transaction history on the Sui Bridge site to see if there's any record of the transaction. If nothing is showing up, the next step is to visit the 'Resume Transaction' page on the Sui Bridge web interface. By entering your transaction hash there, you might find an option to retrieve it. Typically, bridging sites like Sui have this system in place to help resume or complete failed transactions.

Make sure to check the Sui Bridge site at this link: https://bridge.sui.io/bridge-usdc. This is where transactions should typically show up and where you can resume a transaction if it doesn't appear immediately after a timeout. Using your transaction hash on the 'Resume Transaction' page can often rectify the situation and help recover the funds.