HOW I CAN ADJUST THE BRIGHTNESS ON MY LUMIA PHONE

On the Start screen, swipe left, and tap Settings > Brightness.

Automatically adjust is set by default, then the light sensor observes lighting conditions and adjust the illumination of the screen and bottom keys to the environment. When you switch off the automatic brightness control, you can choose between three levels low, medium and high.

When using high brightness settings or when displaying white or vibrant colors the screen will use more energy. Obviously this will also influence battery life.

How I can transfer my music files to my Lumia windows 7

You need to have the appropriate software and the Zune PC app installed on your PC.  You may need to restart your computer, and you may need to install additional software.
Depending on what you need to install, and how much data you are transferring, this may take a while.
Some music files can be protected by digital rights management (DRM). These songs do not appear in your Zune music collection and you can't sync them on your Lumia.

You get an error message trying to access Windows Marketplace for Mobile

You receive one of the following error messages when you try to access Marketplace: 

•	Marketplace could not connect to the server. Please check your data connection and try again.
•	Windows Marketplace for Mobile cannot connect. There may be a problem with the Marketplace service right now. Check your Internet connection and try again.

Solution:

The Marketplace for Mobile service was discontinued on May 22, 2012.
  

Starting on this date, you will no longer be able to browse, buy, or download applications directly on your Windows Mobile 6.x phone by using the Windows Mobile 6.x Marketplace application and service.

How I can reset my Windows Phone 7 to its factory settings

1.	From Start on your Windows Phone, flick left to the App list.
2.	Tap Settings, then tap about.
3.	From the about screen, tap reset your phone, located at the bottom of your screen.
4.	Click yes to confirm your reset.

How I can resize the tiles size on the home screen of Nokia lumia phones to a different size?

Now  you can easily re size the tile size of home screen on windows phone 7.8 and 8 .Just click on the tile and hold it for a second or two and then click on the arrow icon. Depending on the app, the tile can be of two or three different sizes. When you are ready, click the screen. You also readjust tiles. Click and hold a tile, drag and drop it to the new location, and click the screen