Magento 2.0.7 Admin URL missing

[SUMIT619]

I am uning magento 2.0.7, To change the admin url I did this

open /admin 

store configuration>advance>admin>custom admin url

I turned it YES and type "alpha" in the box.  When I click on "save config" than I got 404 not found. 

After this I was unable to open my admin panel. I checked on env.php and I found 

return array (
'backend' =>
array (
'frontName' => 'admin',
),

My changes was not reflected there. I change the code 'frontName' => 'alpha', still I am unable to open my admin panel

I check from ssh my admin url it shows

[root@vp-119045 bin]# php magento info:adminuri

Admin URI: /admin

But I am unable to open my admin panel.

My domain name is cheapmedicineshop.com

Please help me out

[Gabriel Guarino]

Hi @SUMIT619,

The process you followed is correct: The custom admin URL can be found in app/etc/env.php.

Besides that, you can also check the custom admin URL by running the following command in the Magento 2 command line tool:

bin/magento info:adminuri

That being said, this could be related to mod_rewrite not being enabled in your instance. As a result, you should prepend /index.php/ before the custom admin URL.

For example:

http://domain.dev/index.php/sampleadmin

Best regards.
Gabriel