Simple and direct:
* He stumbled over the uneven pavement.
* The runner stumbled and fell, losing his lead.
* I stumbled upon a hidden gem while exploring the city.
Figurative:
* The detective stumbled upon a crucial clue in the case.
* She stumbled through her speech, her words jumbled and unclear.
* The economy is stumbling, with high inflation and rising unemployment.
Focusing on the physical act:
* He stumbled backward, his eyes wide with fear.
* The child stumbled in the doorway, unable to find his balance.
* The horse stumbled and almost fell, its rider desperately trying to regain control.
Focusing on a metaphorical meaning:
* The project stumbled after a series of setbacks.
* Her career stumbled after a public scandal.
* The country is stumbling towards a political crisis.
The best sentence for "stumble" will depend on the specific context you are using it in. Choose a sentence that accurately reflects the meaning you want to convey.