Buttler's men went to the one-day international World Cup in India in October as double world champions but lost six of their nine matches to exit with a whimper.
A four-match Twenty20 series against Pakistan, the team they defeated in the T20 World Cup final in Melbourne in 2022, starts at Headingley on Wednesday.
Both teams will then travel to the tournament in the West Indies and United States.
Reflecting Tuesday on the impact of their poor showing in India, England captain Buttler said: "The pride was obviously dented and it was a really disappointing competition.
"But life moves on, it's a chapter in the book and there's lessons you learn but we're presented with a new opportunity now, in a different format.
"We go to the West Indies and want to give a better account of ourselves. It's a real honour to go to another World Cup as defending champions again but it also feels like a new time."
Buttler was a key voice in England's decision to pull all of their squad members back from the Indian Premier League to prepare as a collective.
The hard-hitting batsman said the IPL should not clash with international cricket.
"As England captain, my main priority is to be playing for England," he said. "It's really important for us to spend this time together.
"Leading into a World Cup, your number one is performing for England and it feels like this is the best preparation.
"But it's my personal opinion there shouldn't be any international cricket that clashes with the IPL - these games have been in the calendar a long time."
Two of England's 15-man squad are unavailable for the opening fixture in Leeds, with Liam Livingstone and Mark Wood both working through knee problems.
Paceman Jofra Archer will make his first England appearance for 14 months but Buttler said it was important not to expect too much from a bowler who has been plagued by injuries.
"We all know what a superstar he has been, but let's manage those expectations," he said. "Don't expect too much, too soon.
"A great success would be him coming through this series with a big smile on his face and his body holding up."
There are questions over Buttler's own availability in the coming days, with his wife Louise expecting the couple's third child.
The vastly experienced Moeen Ali stands by to take the reins if required.
"My family comes first. I'll be at the birth," Buttler said. "I don't think they quite tell you when they're going to come, but we've got a plan in place and fingers crossed everything will go well."
England launch the defence of their T20 World Cup crown on June 4th against Scotland in Barbados.
