I am trying to do migration. I am using 7.9 version. engines start up and search

What I recommend is re-copying the keystore file from the old environment or even better:

1. Re-install Appian
2. Re-migrate the old environment following the migration guide (not that you do have to copy the keystore from the old environment to the new one)
3. Test again

It's not safe to continue to use the environment after so many deletions. The keystore is not being re-created because the Primary DS already knows it was created. There's a way to force it to be re-created but since this environment has clearly experienced multiple wrong attempts to migrate I definitely don't recommend using it.

What I recommend is re-copying the keystore file from the old environment or even better:

1. Re-install Appian
2. Re-migrate the old environment following the migration guide (not that you do have to copy the keystore from the old environment to the new one)
3. Test again

It's not safe to continue to use the environment after so many deletions. The keystore is not being re-created because the Primary DS already knows it was created. There's a way to force it to be re-created but since this environment has clearly experienced multiple wrong attempts to migrate I definitely don't recommend using it.