04-30-2017 07:27 AM
The step-by-step instructions are here.
However, assuming that you can find a copy of the apppropriate version of webOS Doctor (there is a distinct version for all separate devices, including whether your TP was wi-fi only, or was the AT&T version), you will still not be able to restore your system properly because the normal setup process requires access to webOS servers, which no longer exist.
There is a "stickied" thread near the top of this board about bypassing webOS servers to setup your device. But it also leads to links which no longer are active.
You might check out webOS Internals to see if you can find more current information.
In any case, if you are able to restore the TouchPad to operating condition, you will lost all of your own data and third-party apps because, as indicated above, the webOS servers were shut down years ago. Your webOS account backups no longer exist.