No Jar - Bug

[mooch37]

Ok, so whenever you're supposed to combine the 4 potions to make the acid, I only had 3 at the time so I figured, what the hell, I'm here so lets just put these 3 on and I'll go get the 4th after this. Well, the stairs collapsed on the 3rd one so I didn't know what to do. I climbed up, went back to the main room, went down the stairs where the area is supposed to be block by the red vines and they were gone.

So basically here's my problem. I've made it to the machine room now, but I'm missing several things because of that stupid jar. And I would go back except I can't. After you finish the part where the water thing chases you and you see the next big room with the fountain, you cannot go back. So I'm screwed. Without the jar, I can't make the explosive to blow up the rocks that eventually lead to the other rods. Are there any console commands where I can add an item? Oh and I tried to go back to the save point except my earliest save is right after I pass beyond the red vines (THAT I WAS NEVER SUPPOSED TO GET PAST WITHOUT THE ACID).

Sorry, I'm a little cheesed right now because I'm stuck without this vase and because you should be allowed to go back especially for an item that is so important to have. Any suggestions? And restarting the game is not an option.