Let's split the problem into two parts
- Verify if you have the swap partition
- Verify if your swap partition is actually used.
ad 1) Partition /dev/sda7 was the most probably supposed to be the swap partition. Most probably it somehow got damaged, as otherwise filesystem would be recognized as swap.
ad 2) Command free shows you how much swap you have
total used free shared buffers cached
Mem: 3906656 1582008 2324648 78656 41176 916644
-/+ buffers/cache: 624188 3282468
Swap: 8892412 0 8892412
In this case it shows 8GB of swap, none of it's is used.
You may want to reactivate your swap partition.
- Make sure that your partition /dev/sda7 does not contain any valuable data (most probably not)
- Configure type of /dev/sda7 to id 82 (Linux swap / Solaris) you can use both gparted or fdisk to do so.
- Format /dev/sda7 to be a valid swap
- Activate the swap by
- Additionally modify /etc/fstab to make swap start after every boot. The swap line will probably be already there. You will just need to update UUID received as output of 3.