Run tab from android studio bottom toolbar has disappeared

What worked for me in Android Studio 4.0:

View > Appearance -> Tool Window Bars

View -> Tool Windows -> Run

Or use the Alt+4 shortcut key.

For the latest version of Android Studio (4.0+) go to:

View > Appearance > Tool Window Bars

make sure Tool Window Bars is checked.

For older versions:

The following shortcut key doesn't work in Android studio 3.0:

Alt+4.

For anyone who accidentally hides the bottom toolbar due to some configuration etc go to:

View > Tool Buttons (make sure its checked)

This worked for me, the accepted answer only reveals the required view not all of them.

Just putting this in case someone stumbles to this question