Presets

Any presets you saved or imported can be found under the Yours tab, in the presets picker UI.

Is the issue that you reinstalled the app, or installed Lightroom on a new device?  The free version of Lightroom does not sync to cloud storage, so presets will remain as long as the free LR app is not deleted from the device.  The only way to recover would be if you have a device backup you can restore onto your device, where the backup has Lightroom + presets included.

If you did not delete the app, is it possible you recently signed out, and then signed back into Lightroom using a different email address or social signin?  Different email addresses mean different accounts in Lightroom, and it may be possible you could access your presets by signing back into your original account.