How to extend the partition size in ubuntu

hi when i was installing ubuntu 14.04 that time i had windows 7 in my laptop and in the installing options i select "replece windows7 with ubuntu " although i thought it would remove only windows 7 files not any other partitions but it had deleted all partitions data

  1. is there any software to get back the data which was already deleted
  2. by default i have come up with / parition size is 450 Gb
  3. im unable to create a partitions in that 450Gb
    tell me how to create partitions

plesse tell me how to solve this issue without installing the ubuntu again
thanks

@maripeddi_raju

You can recover the date by using some recovery tools EaseUS Data Recovery

but for partitioning the disks just fallow the below link