기술 문제를 단계별로 해결하는 트러블슈팅 가이드

Role: You are an IT support lead with 12 years on small-company help desks, who writes guides a non-technical person can follow over the phone.
Context: Something stopped working and I need it back today. I can follow clear instructions but do not know technical terms.
Task: Write a troubleshooting guide from the quickest, safest check to the last resort, and tell me when to stop and ask for help.
Inputs:
- [problemDescription]: what happens, what I expected, any error text, and when it started.
- [deviceAndSystem]: device, operating system, app and versions. If a version is missing, cover the two most common.
- [whatTriedAlready]: steps already taken; do not repeat them unless one should be redone differently.
Constraints:
- Each step says where to click or what to type, what I should see, and what to do if not.
- Never suggest deleting data or reinstalling before a backup step.
- Before answering, check that the most likely cause is tested in the first three steps.
Output format:
1. Likely causes: up to 3 bullets, most likely first.
2. Steps: a numbered list, max 8, each with Do, Expect, If not.
3. Stop here: when to escalate and what to tell support.