Glad to hear you've got it going again, pky!  I'll still reply, though, since it will happen again.  I've been there often enough myself. LOL

First off, I would agree with what has already been said.  There are natural plateaus to learning or any endeavor, and some days it is harder to find your "drive" than on others.  If you play another instrument, spend some time with that and maybe the change of pace will be enough to get you motivated again.

A day off, occasionally, isn't necessarily a bad thing either.  I would say that if it is not needed more often than maybe once a month, it is nothing major to worry about.  Go out and do something, whatever sort of things you'd normally want to do on a day off.

If possible, even on those days, run a few scales or at least bow some open notes.  Just to make sure it isn't just a day that is just being hard to get started.  At least check your tuning.

If it is a time when you have more than one day that you just don't feel motivated, that's a bit different.  I find it is still best to at least run scales or some very basic things for 15 or 20 minutes at least.  But part of any musician's life is the time we put in, practising and playing.  If possible, you don't want to let that gap get filled by something else.  That is how people end up "not having time to play anymore". 

When you started, you found time, you made the time.  You set aside a part of the day.  There are only 24 hrs in a day, and they all get filled with something.  What you don't want is for that time to be taken up by something else.  If you let that happen, it will.  It is just how the world works.

So try to still spend that time with the instrument and the music.  On such days, sometimes I will use that time to clean the instrument.  Go ever it well with a soft cloth, get it looking as good as the instruments in any shop, if you can.  If you do repairs/maintenance on your instrument(s), it can be a good time to take care of any of the little things you have been meaning to fix or dress up a bit.  Sometimes, by the time you are done, you are already looking forward to seeing how it can sound, and that is the end of the problem.

Or just spend some time admiring the instrument.  After all, part of why you got one in the first place is you liked how they look.  Whether it is showroom shiny or battle-worn from the years, I don't think I have ever seen a musical instrument where I couldn't find some things to admire.  It is part of what you paid for, so it can be good sometimes to take some time to enjoy it.  That can also lead to thinking of things you want to play.

Or maybe go and hunt up some music on the internet, visit a friend who plays, check out some more tutorials.  Maybe you will see something and think "I've gotta try that!" and there you will go again.

Even if none of those things get your motivation back right away, at least you have kept that time slot you made dedicated to your music.  You didn't just let something else take it over and crowd it out.

But I think every musician runs into the problem now and then.  I think of it like when friends who run in distance races like marathons talk about "the wall".  Certain points in any race where the going just seems more difficult.  If you keep moving, you get through it.