The visitors began positively for a side that had gone seven Premier League games without a win.
Villa had fared little better in recent times and were on a five-match winless streak which included losses in their last three league matches.
Villa took the lead when Young's trickery on the left saw him evade the challenge of Kevin Davies and his pinpoint right-footed cross was met firmly by Barry's header.
Bolton's early optimism had been dented within 10 minutes as they failed to pick up the unmarked Villa captain.
Gary Megson's side had earlier seen a header from Helguson sail over and Guthrie shoot wide when unmarked inside the area.
The early goal seemed to breathe life into Villa as they started to play a more expansive game which was reminiscent of the form they had shown before their mini-slump.
Bolton almost levelled fortuitously when Davies crossed and his effort beat Scott Carson but clipped the top of the crossbar.
Young was the central figure early on as he roved from one flank to the other causing Bolton's defence numerous problems.
But the visitors were playing a full share in the game and almost levelled when Matthew Taylor's goalbound free-kick from long range was deflected wide for a corner.
However Bolton almost became the architects of their own downfall when they failed to clear and presented the ball to Martin Laursen, whose shot cannoned to safety off the post.
The visitors began brightly after the interval and forced three corners which were dealt with unconvincingly by Villa's keeper Scott Carson, who flapped at the ball on each occasion.
Villa made the game safe with a second goal which followed the best passage of play in the match.
A swift move which included eight passes saw John Carew link with Young who then found Barry who crossed intelligently for Agbonlahor to prod in from close range.
Villa pushed on and increased their lead further when O'Brien's attempted block only succeeded in deflecting Barry's shot into the net.
Bolton's misery was compounded when substitute Harewood made the most of evading his markers to head in from a free-kick.
The spectre of relegation looms large for Bolton as they remain in the drop zone with five games remaining.
But for Villa hope springs eternal as they hold on to their hopes of securing European football next season.
Aston Villa manager Martin O'Neill: "We got back to basics and we were terrific.
"We had been scoring freely but then we recently hit the buffers.
"The first goal was crucial and we got it through Gareth Barry's header and then our confidence came back.
"We have not been able to keep a clean sheet to save our lives so it was very pleasing to get one."
Bolton boss Gary Megson: "We fell apart after they scored their second goal.
"We have to get up and dust ourselves off and we have to take the criticism.
"We have only taken one point from the last 27 points available but we now have to focus against our game against West Ham next week."
BBC Sport Player Rater man of the match: Gareth Barry 9.21 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.
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Interview: Aston Villa boss Martin O'Neill
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