In any case, to answer this question, I need to give a very very simple explanation of how computer memory works: these days, information in a computer is stored in a code. Just like in morse code, a simple set of symbols can store information. Programs can then interpret the information to display it as words, pictures, etc.
In the case of computers, everything is stored in binary code. These just means that the alphabet that computers use basically only has two letters. We usually talk about these as being zeros and ones. Just like combinations of our normal english alphabet can store the information to spell out a word, a string of ones and zeros in binary can also spell out the information, just in a different format.
So, how is this really stored? Well, to store binary information, we really just need something that has only two states or options. The most common way to do this is by using magnets or capacitors. Why? Well, magnets should be obvious: they're either magnetized with their positive/north pole facing one way, or with their negative/south pole facing that way. Two options for two "letters." If the computer reads a "north" charge, then it can interpret that as a one. South? It must be a zero!
This is how hard drives work. They are large magnetic disks, made of millions upon millions of small pieces (bytes or bits,) each of which can flip its magnetic charge if exposed to the right kind of electric current. To write or store memory, the computer maneuvers something like a needle over a particular bit, and runs an electrical current through it. This flips the bit to positive or negative, north or south, a zero or a one. The bit should stay like that. Now, when the needle moves back to check that bit, it can sense the charge there, thereby "reading" it.
This is why you never want to put a large magnet by the hard drive on a computer. If you do, all the bits in the drive will line themselves up with its magnetic field. This would be like big swaths of letters in a book all turning into just the letter A. A lot of information gets lost.
The alternative is to store electrical charges in capacitors. (You can think of these as tiny batteries.) If there is a charge present, it can indicate a one. No charge? Zero. Capacitors don't store much charge, but what they do store is more or less permanent as far as we're concerned. This is basically how flash drives store binary information.
So, what happens to the binary information stored on a flash drive or magnetic hard drive? When you delete a file, where does it go?
The usual answer is: the file didn't go anywhere. It is still there. In fact, this is one of the big bonuses of forensic science in criminal investigations...people assume that when they delete a file, it goes away. But if you use the right software, you can find the files still there, clear as day. Why?
Well, in general, what normally happens depends on how computers keep track of files. Normally, the program running on the computer knows to store the information for different files in different parts of the drive. This keeps files from being written to the same place. If files are written to the same chunk of bits, then the new file destroys the information for the old file as it changes the bits. It would be like erasing the writing on a paper to write something new.
So, what happens when a file is "deleted" is that the program no longer prevents new files from being written to that space in the drive. It basically pretends the bits there are blank. Over time, as files get written to and stored in the place where the old deleted file was, the information from the old file gets lost as it is written over. This doesn't happen quickly, or even necessarily at all. If you delete a bunch of files and then never use the computer again, the files never get written over, and all the information is still there, hidden on the drive.
The alternative is to physically wipe the drive with a large magnet or huge electrical surge. There are also programs that will write random information over a deleted file's storage area on a disk. They'll do this over and over until the only thing stored there is basically random gibberish: a binary alphabet soup.
The moral is, be careful. Especially these days: drives are so huge and can store so much information that programs may never need to write over old files, because there is plenty of fresh new space left untouched on the drive. This means that pretty much every file you've ever looked at on your computer will still be there, lurking in the drive, ignored but not actually erased.
As for the other question: I'll keep the site up for the time being. I enjoy answering questions! As long as people post questions, I'll likely keep answering...eventually.