How to set my dslr to hdr shooting as default?

Everytime i need to shoot HDR, i have to change the setting so that my camera shoot HDR. (the camera is turning HDR mode after each shoot)
is there's any possibility i can set HDR as the default setting?
i have nikon d5100 if it helps.

Thankfully, no, it's not.

HDR is misused by most of the snappers who have it. Very few photographers use it for more than occasional work.
Learn how to use light and shoot effectively. Then you'll find that HDR just becomes a tool that you use rarely, but you know when you need to use it, and when it's really the wrong thing to do.

Alternatively, you could make it available through your custom settings, Custom F1 allows you to change the use of the self timer button, and you can switch that to HDR on/off. (RTFM page 165)

Your D5100 really does not do good HDR as it only uses two photos. To get good HDRs it takes a minimum of 3 photos.

So you should be setting up for a 3 or 5 shot HDR if you want good ones, which means taking three photos at different EV values and combining them in PhotoMatix or other pp software.

But even then, HDRs should not look surreal - although that is what most HDR shooters want to do. The best HDR photos are those that just improve the dynamic range a bit - to what the eye naturally sees.

HDR isn't standard hence it shouldn't be default.