Write a query to display the names of users who have been working in TCS in the year 2012, sorted in order.

You are getting errors because you have used reserved words for column and table names user, end, name.

All you need to do is surround those names with square brackets i.e.

select [name] 
from [user] where profile_id in 
(
	select profile_id 
	from experience where company_name='TCS' and ((year([end])>='2012' and year(start)<='2012') or [end] is null)
) order by [name];

Your checking of year(end) is also a little messy - you only need to check for equality because you are only looking at the datepart Year...

select [name] 
from [user] where profile_id in 
(
	select profile_id 
	from experience where company_name='TCS' and (year([end]) = 2012 or [end] is null)
) order by [name];

A better approach to using the sub-query on table experience would be to use an INNER JOIN - that way only data that matches both tables will be returned. I.e.

select [name] 
from [user] U
INNER JOIN experience E ON U.profile_id = E.profile_id
where E.company_name='TCS' and (year(E.[end]) = 2012 or E.[end] is null)
order by [name];