well to be honest i don't know what is the problem can you run php command from console? like php echo hello if you return with only hello then i guess you don't need to be have any problems running your forum. If there is something messed by me then i am sorry i am not familiar with ubuntu.
Well, I'm lost. I still cannot figure out what the problem is. Nothing seems to be helping. Thanks for your help anyways Dark Power.
Why don't you try to install it from beginning?.
Already tried that many times, it didn't work. However, I finally fixed my problem. It seems like it was misconfigured in the mybb.config. It's all fixed now. Thank you all for your help.