chance on vs regain

chance on and regain both are verbs.

Word	Noun	Adjective	Verb	Adverb
chance on	No	No	Yes	No
regain	No	No	Yes	No

As verbs, regain is a hypernym of chance on; that is, regain is a word with a broader meaning than chance on:

chance on: find unexpectedly
regain: come upon after searching; find the location of something that was missed or lost

Other hypernyms of chance on include find.

chance on (verb)	regain (verb)
find unexpectedly	get or find back; recover the use of
	come upon after searching; find the location of something that was missed or lost