If suddenly you find that the calendar widget only shows calendar events occurring today, not those coming up in the next few days as it used to or you cannot get your email to sync more than you have it set then it may be an issue with your data allowance. For example, you want to synchronize all the email in your inbox but it will only synchronize email from the last 24 hours.
Issues where your settings are correct and there is no other explanation may have to do with your data allowance. Check to see if you are over your data allowance. If you are, your phone will change the settings to not exchange any data over the mobile network – even when using Wi-Fi.
To fix this, change your phone setting to allow data exchange. You may need to do a 'Fetch all' in TouchDown to start synchronizing emails correctly and have the calendar widget display correctly.