I ran out of Water Bombs in the Lakebed temple, and I'm at the part right before the mini-boss. I've gotten out, but for the life of me I can NOT get back into Hyrule field. Help!
Oh trust me, you don't need to get back out into Hyrule Field. Right near the entrance to the Lake Bed temple (in the area with the Zoras swimming around) there is a Zora who'll sell you Water Bombs. They're a bit more expensive than if you got them from Barnes, but with how common Rupees are, you've probably got plenty enough for some Water Bombs.
There are many waterbombs to be found in the Lakebed Temple. Like Master Kokiri said but also in the entrance where you have to shoot those things from the ceiling you find a chest on the left side next to the door with Waterbombs. There are also bombs in the chest where you have to go up and flip the lever. The one where you also will find the Compass. When you return there for the second time you will find bombs again at the same spot. There are waterbombs in the room with the rotating platforms where you have to climb the vines up. If you really used them all you can easily go back to buy bombs but you need Ooccoo.
Go back to the room with the rotating stairs. Walk up and keep on walking around till you find the pot with Occoo in it. Use Ooccoo to warp out and go buy bombs. Ooccoo will return you to exact the same spot where you left once you are done with buying bombs
Just call epona and ride there. If that does not work, Save, shut down your wii, and turn it back on and try again. If that wont work it may be a rare issue or something unique to your home set up. Please call 1-800-255-3700 so that nintendo can assist you further.
Either get shot out of the lake with the canon, and if you don't have enough money for the Zora's bombs, you can get shot up, get the 100 ruppee pize, and repeat until you have a full wallet.