1. if you have changed program and did not get another I-20, you have been out of status.
2. You can ask for a new I-94 ONLY if you have a unexpired F1 visa stamp. You have to use your old I-94 to re-enter if you don;t have a valid visa stamp.
The stamping on I-20? Hard to say. Because it's not a "new" entry, (the time you used a visa and filled out an blank I-94 to enter was a new entry and is still your last entry) they don't have to stamp your I-20 for entering using old I-94 under auto visa revalidation within North America.
2. You can ask for a new I-94 ONLY if you have a unexpired F1 visa stamp. You have to use your old I-94 to re-enter if you don;t have a valid visa stamp.
The stamping on I-20? Hard to say. Because it's not a "new" entry, (the time you used a visa and filled out an blank I-94 to enter was a new entry and is still your last entry) they don't have to stamp your I-20 for entering using old I-94 under auto visa revalidation within North America.