Unable to Access WordPress via WAMP

Hi all.
I have WordPress running on a localhost using WAMP.
On Day 1, all works fine. WANP and it’s services are up and running and I install WordPress and start the customization process.
However.
When I come back the next day to continue work on the website, I am unable to access it via the WP_Admin screen. It says my username and/or password is invalid.
The only difference between the two days is that overnight I had stopped the WAMP Services when i turned my PC off, as I usually do each night.
Why does this happen and how can I “beat” it ?
Thanks in anticipation.
Cheers,