You failed to pay Mohamm3D L$10000!!!!!

[Braveless]

i got messege said :You failed to pay Mohamm3D L$10000.after that i lost 1000 lenden!

[Rolig Loon]

You can't "lose" L$10000 unless you gave someone permission to take it.  Nobody can reach into your account and take money without your permission.  Unfortunately, it is easy for a clever scam artist to get some people confused, especially if they are new to Second Life or do not speak English well. You probably clicked on some object or accepted a gift from a stranger and then wore it, ignoring the automatic warning that asks your permission to transfer L$.  The sad lesson from this is that you should NEVER give permission without knowing who is asking for your money and why.

If you have the name of the person, you can try submitting an Abuse Report with all of the details. Your chances of getting the money back are quite small, however.  The transaction will appear on your Transaction Report as a "gift", so there is no way to prove that you didn't give the money willingly.

[Syo Emerald]

Sounds like you wasn't paying attention to what you agree to. I assume you somehow encountered an object that asked for your permissions and you simply agreed to it, without reading what exactly you got asked. The result was, that this object now had your permission to get money from you. I assume it was scripted to take 10.000L$, but because you didn't have that much, it took what was there.

Sorry to say that, but you won't see your money ever again.

[Lindal Kidd]

I will add to the other excellent answers.

As they told you, this was most likely done by an object that somebody gave you.  When you rezzed it, it asked for permission to "take Linden Dollars from you" and you clicked "Allow."

If you left the object rezzed somewhere, it can CONTINUE to take money from your account, every time you buy more $L.  Go to where you rezzed it, and delete it!