Re: Not able to find store in windows 10 tech preview in my lumia 625
A quick suggestion and a question. It may not have shown up on the home screen upon upgrade. Is it seen on the apps list? If so, you can long touch and pin to the home screen from there.
If it doesn't show in the apps list, do a soft reset (hold volume button and power button down for about 10 - 15 seconds until you feel the second vibration). This may bring it up. If this doesn't work, there are a couple of things to try.
Do a hard reset of the phone making sure you have backed up your data. This many times corrects such mistakes in original upgrade.
If this doesn't work, use the Lumia Software Recovery software and restore Win 8.1 and then try the upgrade again.
I'm sure a Mod will move this to the WP phone section and you will get many more suggestions.
Good Luck.