I've recently deleted Boot Camp downloads and storage has disappeared /dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:         Microsoft Reserved                         16.8 MB    disk0s2
   3:                 Apple_APFS Container disk1         58.5 GB    disk0s3
   4:                        EFI NO NAME                 104.9 MB   disk0s4

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +58.5 GB    disk1
                                 Physical Store disk0s3
   1:                APFS Volume Mac OS X                18.0 GB    disk1s1
   2:                APFS Volume Preboot                 21.4 MB    disk1s2
   3:                APFS Volume Recovery                518.1 MB   disk1s3
   4:                APFS Volume VM                      1.1 GB     disk1s4

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *31.0 GB    disk2
   1:                 DOS_FAT_32 WININSTALL              31.0 GB    disk2s1


Can anyone tell me what happened? and how do I restore it? disk0 is the one missing storage and disk 1 is the one I'm using. I don't know much about computers. 
I've downloaded windows software using bootcamp. When I reboot and got into the installation page for windows, it asked me to choose partition to install windows. I accidentally deleted one of the partition, which is now called NO NAME. I quitted the installation and back to OS. In disk utility NO NAME cannot be found. By selecting my current disk, I press "+" multiple time and then press "-" until i was back to a single partition, it shows that i have 165 GB (original amount). But when i press "apply", I cannot partition my current disk.
To remove Boot Camp, one is meant to use Boot Camp Assistant which provides an automated workflow for editing the partitions on your disk back to pre-Windows. You may still be able to use it in this state — try opening Boot Camp Assistant and choose Remove Windows if the option exists.

You can partition manually in Disk Utility. Choose Partition, delete NO NAME and resize the APFS container to the rest of the free space on the disk.