The Genius Bar is good at identifying a failing drive and will tell you so. What follows is a repair — and a repair means the failed drive leaves with the old parts. Which is why the sequence matters more than anything else here.
Repair is measured by whether the Mac works afterwards. Recovery is measured by whether your files come back. On a failing drive those objectives pull in opposite directions, and the order matters.
Apple's service process replaces components. It does not recover data, and Apple say so explicitly — their terms make clear that you are responsible for backing up before service and that data may be lost.
In practice that means a Mac sent for repair with a failed drive frequently comes back with a new drive fitted and the original discarded. If the data mattered, that is the worst possible outcome, and it happens because people reasonably assume a manufacturer repair includes their files.
If the data matters more than the machine, go to a recovery laboratory first and Apple afterwards.
A failed drive on a pre-2018 Mac. Apple replaces it. The old drive is not returned and your data goes with it. Recover first.
A T2 or Apple Silicon machine with a dead board. Nobody can recover this, including Apple. The key is fused into the security chip on that board.
A T2 or Apple Silicon machine that still powers on. Data can frequently be extracted before service, either by you or by a laboratory. Do this before sending it.
An iCloud account problem. This is Apple's territory rather than ours. Support can help with account access, which a recovery lab cannot.
No. They will diagnose the hardware and offer repair or replacement. Data recovery is explicitly outside what Apple provides.
Ask before the repair, and get it in writing. By default replaced components are not returned.
Recovery first if the data matters, then repair. Doing it the other way round frequently loses the data permanently.
From £300 +VAT where the storage is removable, which covers every Mac up to roughly 2017 and many after.