Reports of data theft often conjure up images of malicious hackers breaking into remote databases to filch Social Security numbers, credit card records and other personal information. But a lot of the time, the scenario is much simpler: A careless worker at company or agency with weak security policies falls prey to a low-tech street thug who runs off with a laptop loaded with private data. In the biggest case, the Department of Veterans Affairs recently lost data on 26.5 million veterans and military personnel stored on a laptop and external drive stolen from the suburban Washington home of a VA employee. Security experts and some privacy groups say simple measures could protect data if a laptop falls into nefarious hands. They include encrypting the information so it’s nearly impossible to access without the correct credentials.