How to reply when she messages first then disappears for a week

A week is long enough that she either forgot you exist or deprioritized you on purpose. Both happen. Neither means she hates you. What matters is that she did message first, which means there was a real reason. She wanted to talk to you at that moment.

When she reappears, she's probably feeling a bit sheepish or assuming you've moved on. Don't reward the silence with extra attention. Don't punish it either. Treat her like someone who messaged you yesterday, not like someone who owes you an explanation. The silence is the message. Your job is to move forward, not to litigate what happened during those seven days.

Your message needs to do two things. First, it has to make it clear you're not mad or waiting for an apology. A normal, warm tone does this better than jokes about ghosting. Second, it has to ask her something or bring her into a moment that's actually interesting. Generic catchup questions work, but reference something from her profile or something she said in that first message if you can. This shows you paid attention and aren't sending the same thing to ten people.

Don't be long. Don't be clever or needy. Short and open beats everything here. You're basically saying: I'm still here, and there's something worth talking about.

Send your message and wait about three days. If she doesn't reply, that's your answer. She had her moment of interest and it passed. You don't send another message. You don't follow up in a week asking if she's alive. One reply is your limit in this situation.

If she does reply, proceed like a normal conversation. Don't bring up the silence unless she does. If it happens again, the pattern is telling you something about how she communicates. Most people ghost once by accident. Twice means this is who she is.