Scenario 1 - Go Around (carefully - flaps aren't moving so watch the limit speeds). QRH. Landing distance. Decide where you want to go. Do it. On a very nice sunny day you may want to keep a very close eye on fuel burn and fuel flow as you may be into your reserves fairly quickly if you are stuck at high flap settings. Do not trust FMC fuel predictions - use fuel flow and do it the old fashioned way.
Scenario 2 - Surely if your departure field is unavailable after departure, you should have a takeoff alternate already? Level off, QRH. Pick an alternate. With flaps stuck at a takeoff setting (you could be only Flap 1), you may need a nice long runway. As above, remember fuel predictions from the FMC are rubbish, so check your fuel flow at your cruise level. Also remember you are limited to FL200 with flaps extended.