Hey there....any Android dev here to help me with this bug?

You need to specify an activity in the AndroidManifest that should be launched upon launching the app.

There is a property called "android:name" which has the value of activity you want to start the first time the app launches.

Either you removed MainActivity.java or you changed it in the Manifest.

Either way put the name of the activity you want to launch first in "android:name" in the Manifest file.

Have removed main activity en created another one...thanks @kalolparty

Salute @joas