Q: If you fall down and get up by yourself, which expression is grammatically appropriate: “When I fall down, I rise myself” or “When I fall down, I raise myself”?
A: This sentence is correct: “When I fall down, I raise myself.”
The verb “raise” here requires an object, the thing (or, in this case, the person) being raised.
However, the verb “rise” does not need an object. So this sentence would also be correct: “When I fall down, I rise.”
If you want to emphasize that you get up without any help when you fall down, you could say: “When I fall down, I rise by myself.”
The construction “rise myself” is ungrammatical.
If you’d like to read more, we’ve discussed “raise” vs. “rise” before on the blog, as well as another confusing pair of verbs: “set” and “sit.”