Hello nimati,
Adobe's PDF Reader has for selecting text only it's "normal" selection tool. It gets problems in case Unicode characters or non-embedded fonts are used in a document. The "TouchUp Text tool" for the advanced PDF editor is powerful, but it's included only in the Acrobat Professional version.
Another thing could help, did you already try to print the pdf file to CutePDF printer? From the new document you should be able to copy and paste the text.
Hans-Günter