The unnamed woman, who is now living in Wales, wrote to Frances Cunningham, the owner of the Swettenham Arms near Congleton, Cheshire, detailing the 1992 break-in.
She wrote: "I was involved in a burglary at your business in 1992 approx.
"I didn't break in or smash up the ciggarette (sic) machine but I was there and I went in.
"I am very very sorry I did not realise the seriousness of my actions at the time I had been through alot (sic) and had no idea were (sic) to get help.
"I am ashamed and sad because of the fear it may of induced and the cost and time. I wish I could take it back alot (sic).
"I hope that you will never be bothered by such cruelty ever again."
The letter concludes: "P.S. If there are any further costs, let me know."
Mrs Cunningham, who took over the pub in 1993, said: "I think she's got a conscience and worried about this for a very long time and I hope she doesn't worry about it anymore.
"She's obviously been blaming herself and worrying. I shall now right back to her and thank her."
Mrs Cunningham has donated the £100 to her local church.
More top news
Staying windy and unsettled
David Cameron has admitted the General Election is on a "knife-edge" as he tried to woo voters with the promise of a "truly seven-day" NHS.
Two murderers who wed in Britain's first gay prison marriage will not be allowed to share a cell.