For seemingly unexplained reasons my DSL is (often several times a day regardless of the weather) interrupted and sometimes we wait for it to come back but mostly we reset the router by switching the power off & back on in a minute or so.
You'll want to post some additional information. From what I've read on these forums, the system log and transceiver statistics are helpful in diagnosing your problem.
To get them...
I'm not a tech but saw your post and thought I could help speed the answering process up for you.