First of all, after he tried to kill Harry, his body was destroyed or at least killed. The remaining piece of his soul was separated and (unable to move into the world of the dead thanks to Horcruxes) hung around. To quote the dude himself from "GoF":
"You all know that on the night I lost my powers and my body, I tried to kill him."
...
".... I was ripped from my body, I was less than spirit, less than the meanest ghost. . . but still, I was alive. What I was, even I do not know... "
...
"...Nevertheless, I was as powerless as the weakest creature alive, and without the means to help myself...for I had no body, and every spell that might have helped me required the use of a wand. . . ."
... "Only one power remained to me. I could possess the bodies of others."
To answer the second question, it was explained.
Wormtail found him in Albanian forest where he hid all those years (same place he retrieved Ravenclaw's Diadem many years before when Gray Lady and Bloody Baron died without retrieving it).
(GoF again) ... "I settled in a faraway place, in a forest, and I waited".
and, talking of Wormtail:
He sought me in the country where it had long been rumored I was hiding . . . helped, of course, by the rats he met along the way.
... His filthy little friends [rats] told him there was a place, deep in an Albanian forest, that they avoided...
And of course, we find out why it was Albania in Deathly Hallows when Harry talks to Gray Lady about the Lost Diadem of Ravenclaw:
“And . . . and the diadem?”
“It remained where I had hidden it when I heard the Baron blundering through the forest toward me. Concealed inside a hollow tree.”
“A hollow tree?” repeated Harry. “What tree? Where was this?”
“A forest in Albania. A lonely place I thought was far beyond my mother’s reach.”
“Albania,” repeated Harry. Sense was emerging miraculously from confusion, and now he understood why she was telling him what she had denied Dumbledore and Flitwick. “You’ve already told someone this story, haven’t you? Another student?”
...
So Voldemort had managed to wheedle the location of the lost diadem out of the Gray Lady. He had traveled to that far-flung forest and retrieved the diadem from its hiding place, perhaps as soon as he left Hogwarts, before he even started work at Borgin and Burkes.
And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years?
