With the increased risk of identity theft, you can never be too careful when handling your personal financial information. The FTC requires that companies now truncate the numbers on a credit card receipt to help protect consumer's personal information. This may lead to being a little less careful about keeping track of your receipts, but sometimes you need a receipt for proof of purchase. If you used your card, then getting a copy of the receipt or other form of proof should be no problem. Companies are required to keep track of all transactions, so just follow the paper trail.
Check your bank statement online or at a bank to get the exact amount and day the charge was made. Print this out for confirmation. Usually this is enough to serve as proof of purchase.
Call the company from which you purchased goods or services and ask for a copy of your receipt. They should be able to search through their paperwork and get the original receipt and either reprint it or send you a fax.
Call the company headquarters to get a copy if the store no longer has the receipt on hand. Businesses are required to keep paperwork for credit card transactions, so be persistent.