My suggestion: Remove the chain and soak it in some degreaser for a day, give it some shaking, basically loosen all the old dust that has bonded to the old oil in the chain. Then, toothbrush the hell outta it.
Then take some time to lube it. There's a lot of expensive "Chain Oils" out there, but for the most part, you don't need to bother with them. I believe you can cut some ATF with a bit of mineral spirits and make a fine chain lube. Hell, you could probably use straight ATF. Either way, lube every link, and then wipe away the excess. Then pop the chain back on.
Then, when you have it back on, check the front derailer when you have the chain on the large chainring. The cage should NOT be touching the chain at all. Also, not sure of your memory, but try not to cross-chain, which is running in the "Large-large" or "small-small" configuration, where the chain is on the largest cog and largest chainring, or smallest and smallest. This puts a little too much lateral stress on the chain and can lead to skipping, and excessive wear. If the cage is rubbing, there are a pair of small screws near the mount of the derailer that you can adjust. They affect the maximum range of the cage. Look for the HI or H marked on, and see if you can adjust the cage to clear the chain.
Of course, depending on how much you rode it before throwing it into the rafters, the chain might be worn out. Bike shops have a gauge for that, and will usually will do it for you without charge if you ask nicely :D (It's a 2 second job). New chain is available and cheap, and can be had from pretty much anywhere. But if you can, find one with a "Power-Link" which is a link with a tool-less opening link. So much easier!