So, why does that happen?
And how to fix the SSD unallocated issue?
Read this post on theMiniTool Websiteand you will find the answers.

Why Is My SSD Unallocated?
So why does the Unallocated happen?
You may consider the following aspects according to your situation:
1.

Your unusedSSD has not been initialized.
The existing partitions have been deleted.
The drive has been formatted with a file system that is not supported by the machine.

The partition table has been corrupted or deleted.
Lost or deleted SSD volume.
it’s possible for you to directly create a new partition for that.

Step 1: OpenRunby pressingWin + Rand typediskmgmt.mscto enterDisk Management.
Step 2: Right-hit the unallocated space to chooseNew Simple Volume…and clickNext.
Then you’re able to follow the on-screen instructions to configure the prefs and format the partition.

After that, you could start using it.
To merge unallocated SSD space, it’s possible for you to do as follows.
Step 1: OpenDisk Managementand right-go for the partition you want to extend to chooseExtend Volume…. Then your unallocated drive can be used in the extended partition.

Part 2: How to Fix the SSD Unallocated Issue?
you better follow some troubleshooting methods as the next moves.
Step 1: Right-choose theStarticon and chooseDevice Manager.
Step 2: ExpandDisk Driverand right-tap on the SSD drive to chooseUpdate driver.
Step 3: ChooseSearch automatically for driversand follow the next prompts to finish the work.
Then reboot your setup to verify if the issue has been resolved.
You may use it to fix the SSD unallocated issue.
Step 1:OpenFile Explorerand thenThis PC; right-punch the SSD drive to chooseProperties.
Step 2: In theToolstab, clickCheckin theError checkingsection and clickRepair driveto go on with the fix.
Then follow the prompts to repair the issue and reset your setup.
However, this method will erase all the data in your drive.
If the data in your drive is not that important, it is worth trying!
The steps are as same as theWay 1.
Create a New Partition, because, in this process, your drive will be formatted for use.
It is worthwhile to try and you will be surprised by its powerful functions.
you’re free to follow to configure the tweaks.
Step 3: When you have everything done, clickFinish > Applyto start the task.
You might hold a fluke mind in relying on the data recovery software when it happens again.
However, some data loss incidents are unrecoverable and the only resort is data backup.
None of your data can be lost.
Many people will choose todevelop a backup planas their prime guarantee.
MiniTool ShadowMaker freeis a prime choice for consumers.
Withbackup schemesand schedules, it can shorten your backup time and minimize resource consumption.
The user experience gets optimized and specific features allow users to produce a backup plan tailored to themselves.
SM-Trial
Step 1: Go to theBackuptab and chooseSOURCE.
Here, you’ve got the option to chooseDisk and PartitionsandFolders and Files.
Step 2: Then go toDESTINATIONto choose where to save the backup and clickBack Up Now.
Bottom Line:
Still struggle with the SSD unallocated issue?
The above solutions may have resolved your issue.
However, once the issue occurs, most likely your data has been lost.
Foster a good backup habit and your data can be better protected.