there are three passwords to be aware of. They are spfarm, spsearch and spwebapp. Here is set of instructions is how to reset the spfarm account password.
Steps from TechNet :Reset the AD password for the out-of-sync account(s), the accounts can be found under MyBusiness>Users>SBSUsers. Please see above for more information on the accounts. Note: Be sure to uncheck “User must change password at next logon” Sync the password for the account(s) from elevated SharePoint 2010 Management Shell (replace accountname with the affected account):
Set-SPManagedAccount -UseExistingPassword -Identity $env:userdomain\accountname Run repair to verify that passwords are synced:
Another Reason Copmpany web may fail:
Use explorer to open the following location C:\Users\Default\AppData\Local\Microsoft\Exchange Server\v14. For each file in this folder identified in the matching event (Configuration14400_100.sqm in our example), open its Properties. Select the Security Tab. Click Advanced. Click Continue. Check the “Include inheritable permissions from this object’s parent” checkbox. Repeatedly click Ok to close all the dialogs. From an administrative command prompt, run IISRESET /noforce
Note: you may have to run this command several times until it concludes successfully.