We're sorry about the trouble with Lightroom & due to the missing images.
Since you are using the free version of Lightroom mobile, the images you imported would have been saved on the phones local storage only and not synced to the cloud storage. Uninstalling the app and re-installing it may have removed all data associated with the app including your imported images and presets.
You can try connecting your phone to the computer and navigate to the Lightroom folder on the internal storage to check if you are able to locate any images. You can also check the com.adobe.lrmobile folder in the internal storage of the phone > Android > data > com.adobe.lrmobile > files