I have a point shp file of 445 points around the globe, that i need to create buffer-zone of 10 km around each point, the points shp file is in wgs1984 geographic coordinate and wgs1984 platte carre as projected coordinate system. Every time i create the buffer zone it gives me a HUGE circles above each other that cover the area of whole points together and more!. Does anyone knows why is this happening?
ArcGis attempts to project your data when doing a buffer in inappropriate units, this works for smaller datasets, it cannot do this if the points are dispersed all over the globe as it can't pick one to suit the whole dataset.
You are going to need to do each point (or cluster) individually, projecting to an appropriate projected coordinate system. For example this image illustrating how the earth distorts:
Australia is the same size as China and it's much worse at the poles!
Kilometres is not a valid measurement in geographic coordinates as the conversion depends on which part of the globe the point is, thus the data needs to be projected to a metre based coordinate system (UTM, Conic..) but you cannot project everything into the same projected coordnate system (it just doesn't work that way). After buffering project back to geographic if you need it in geographic. Note, your circles will become ovals.
If you need circles of approximately 10km in geographic coordinates you will need to find out what the conversion is at each point, insert that as an attribute and buffer by attribute... this will not be perfect by any means.
Which method you use depends on the weight you put on accuracy vs visual appeal.
If you look in your Arc install location reference systems folder (for example: C:\Program Files (x86)\ArcGIS\Desktop10.1\Reference Systems) there is a shapefile called UTM which you can intersect with your points to divide them amongst the valid UTM zones for projection (use Intersect or Spatial Join) then select the points by each unique ZONE_ID and project/save as and buffer then create an empty feature class in WGS84/Geographic and append the buffers (this will project them at the same time) to merge. Note, if you want attributes to be copied ensure that the empty geographic shape file has the required fields.