I took ranitidine at around 1pm and rhen took prilosec at around 8pm still no relief. can i take another ranitidine right now at 9pm?

Yes you may: But firstly why are you taking the medications. If diagnosed with GERD then follow Reflux precautions. If Gastritis or ulcer discuss with your doctor if treatment is required for H pylori and follow ulcer precautions

You can, but...: You didn't specify the strength of either medicine so I'm assuming you mean the OTC versions. You can take another and it may benefit you, but it is often more effective to use an antacid to calm your stomach more quickly. I personally prefer Gelusil but any brand will work. Either way, if this persists I would see your doctor and see if you would benefit from medical treatment.

Incorrect procedure: You need to take your Prilosec in the morning about 30-60 mins before your first meal and not in the evening unless you are on a night-shift schedule. Ranitidine may be taken around your meals if needed. However if you do need both to control your symptoms, you need to consult a GI doctor . The answer is yes , you may take another ranitidine at 9 p.m.