1. When I'm worried about something, I follow my parents' advice.

"follow" and "take" are the best verbs to use for this expresssion. So 1 and 3 are correct. 2 would be better if you simply omit the apostrophe and the word "advice."

Yes, all the sentences are grammatical. In sentence #4, there are a few suitable verbs that can be used in the blank to convey following or heeding parents' advice when worried about something:

1. "heed" - This verb means to pay attention to or take notice of someone's advice. For example, "When I'm worried about something, I heed my parents' advice."

2. "follow" - This verb means to act in accordance with or adhere to someone's advice. For example, "When I'm worried about something, I follow my parents' advice."

3. "listen to" - This verb phrase means to pay attention to and consider someone's advice. For example, "When I'm worried about something, I listen to my parents' advice."

4. "adhere to" - This verb phrase means to stick to or comply with someone's advice. For example, "When I'm worried about something, I adhere to my parents' advice."

These are just a few examples, but there may be other suitable verbs depending on the specific context or intention of the sentence.