If a Hard Reset by the two buttons your pressing isn't working after trying a few times then as the phone is still under its 2 Year Manufacturing Warranty you can pop it into a Vodafone Highstreet Store where they'll take a look and if necessary send it off to their repair house.
Manufacturing Warranty wouldn't cover issues from a drop or water damage. So if a phones casing is marked up or screen cracked they'd may determine that as it's been dropped.
As part of the repair process they will most probably try and restore it which takes it back to the last firmware update which will invariably delete your saved data.
If you haven't set the phone to automatically back up to any type of online vault provided by Google or Dropbox as examples or set things to go into any inserted Sd card and contacts in somewhere like gmail then your information / data will most probably be lost through their reset process on the phone.
Tip >
If it's going to be sent Off > Take time and date stamped pictures of the phone with one of it turned On if possible to prove its aesthetic condition and ask the employee to note its condition.
If the water sensor is visible then take a picture of that too.
Ask if your Account allows you to be given a Courtesy Phone to use in the interim. (Stock availability permitting)
"Also make sure when sending your device for repair that you keep hold of your SIM. You also shouldn't send your memory cards, battery and/or back cover (if they're removable) - if these are included with your phone when it goes for repair we can't guarantee their return."
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.
