Try and Regret: Gerund or Infinitive? (B1 Grammar)

Use try + to + verb for an effort that may fail; use try + -ing to test a possible fix.

try: make an effort, or test it out

Lars: I tried to fix my old chair last night, but it's still broken.
Diego: Try watching a video online. It might help.
Not "I tried hard remembering her name, but I couldn't." — say "I tried hard to remember her name, but I couldn't.". An effort, especially with hard, takes try to: tried hard to remember.
Try it: Lars: Why is the window still closed? It's so hot in here. Lars: Your plant looks much better. What did you do? Match each line to a reply. Answer: Lars: Why is the window still closed? It's so hot in here. → I tried hard to open it, but it's stuck. · Lars: Your plant looks much better. What did you do? → I tried moving it to the window. — An effort that fails takes try to; testing a possible fix takes try + -ing.

Use regret + -ing when you are sorry about something you did; regret to say / tell / inform formally breaks bad news.

Lars: Attention, please. We regret to say that today's guided walk is canceled.
Diego: That's a shame. I regret not coming last week, then.
Not "I regret to lend him the money. (meaning: I lent it, and I'm sorry)" — say "I regret lending him the money. (meaning: I lent it, and I'm sorry)". To be sorry about something you already did, use the -ing form: regret lending.
Try it: Ira: Your friend moved to a bigger apartment, right? Does he like it? Choose the reply that fits. (Not really. He regrets moving. / Not really. He regrets to move.) Answer: Not really. He regrets moving. — He moved and is sorry about it, so use regret + -ing: regrets moving.

Incorrect	Correct	Why
I tried hard remembering her name, but I couldn't.	I tried hard to remember her name, but I couldn't.	An effort, especially with hard, takes try to: tried hard to remember.
I regret to lend him the money. (meaning: I lent it, and I'm sorry)	I regret lending him the money. (meaning: I lent it, and I'm sorry)	To be sorry about something you already did, use the -ing form: regret lending.