If all else fails
Definition 1 of 1
Pro Tip 1/3Last Resort
Use it to describe an action you take when nothing else works or is available. 
I'll try emailing and calling her, but if all else fails, I'll just drop by her office.
Pro Tip 2/3Subtle Urgency
Implies a sense of urgency or a final attempt after other methods have failed. 
Please fix the server tonight, but if all else fails, we'll need to call in outside help.
Pro Tip 3/3Casual Tone
It's mostly used in casual or informal conversations rather than formal writing. 
Look for her at the game, but if all else fails, text her.