We use MISS in these cases:
1. Failure to attend or to get something
a. Transportations(buses, trains…)
- I missed the 8:00 train, so I had to take the 9:00 one.
- Alan, you missed a great concert last night.
- You missed class on Friday.
2. When someone is away from you and you wish they were with you.
- My sister moved to Vietnam last year. I really miss her!
- I miss my girlfriend. She’s on holiday with her family.
We use LOSE in these cases:
1. When you can’t find something or something’s gone.
- I lost my dog. Please help me to find him.
b. Sports games:
- My favorite football team lost 5-1 in the semifinal.
2. When someone is gone from your life.
- I lost my Grandmother last year.
- I've lost my girlfriend. We had a messy break up and I don't think I'll ever see her again.
- She lost her husband during the war.