unused schengen visa

[logical_1]

A friend of mine has been issued with a schengen visa but unfortunately he won't be able to travel as some unexpected things came up.
I would like to know that if he doesn't use his visa will it affect his future applications as he doesn't want to jeopardise future applications.
Many thanks.

[sheraz7]

Usually violating the visa conditions can affect the future application but not travelling after getting schengen visa should not cause any problem for future application as the plans can be changed due to personal reasons/natural disaster etc. Keeping some evidence that has prevented from travelling maybe helpful too for future (if being asked).