There are several safe ways to try to reinstall a missing or corrupted msvcr71.dll file in Windows. Try restoring the file from the Recycle Bin, or use a free file recovery program. Also, run a virus scan, or try undoing any recent system changes with the System Restore tool.
Some other ways you can reinstall the missing msvcr71.dll file include reinstalling any recently installed applications and making sure that your Windows system is up-to-date, as the msvcr71.dll may actually be outdated, rather than missing or corrupted. Also, try performing registry maintenance using a registry cleaning software, as this can help repair your registry and keep it error-free.
Updating any hardware drivers, such as for your video card, may also resolve this issue. Alternatively, you can try rolling back a hardware driver if the msvcr71.dll file missing error started after you updated a driver. If that doesn't work, try running the System File Checker tool. If the issue is still not fixed, run a repair of your Windows installation. Finally, if none of these methods help, test the computer's memory and hard drive for errors. If they fail the tests, they are the likely causes of the missing msvcr71.dll file issue and need to be replaced.