First of all, you can delete all the files on Nokia C drive! Here are some pictures or sounds that are usually stored! You can cut to e disk if you need it! Then there is the folder under system\app on drive C. You can see a ByRead-like folder with the same name as the software you use! My example is Baiyue. If you still use this software, keep it. If the software is no longer in your mobile phone, delete it! Then there are two folders, GameMgr and GameMgrUi. Open them and see if there are files of games you don't play. Look at the comparison between the name and disk e. Generally, it is 6R33, 6R45 and 6R49. Delete it if it doesn't work! Look at the folder system\codecs on drive C, which was left by Smart Cinema. Leave it after use, and delete it if it is useless. Then look up Notepad.dat in C\system\data. It's a notepad file, which can be saved in e disk at ordinary times! And this C\system\data\Contacts.cdb file is a business card file. Look at its size, if your business card does not exceed 300, it should not exceed 100K. If it exceeds 300, it needs adjustment. The operation is as follows: after entering the business card folder, select, move down to see [Exit] and click, and repeat the operation until the file just now is less than 100 K. Looking down, the folder C\system\install can be completely deleted. It's just an installation record, which is generally useless! C\system\Mail Here is the information file, which can be reduced by deleting useless information. Usually, it's best to transfer the pictures and ringtones received through Bluetooth to the disk, and don't leave them in the message, which takes up a lot of memory! Finally, did c \ system \ shareddata \ reserve.bin find this file? It's 64k, and it's a useless file. I usually delete it! But the system will automatically generate it. You can copy its name first and then delete it, then create a new folder with the name you just copied, and then set the properties of the folder. Just open the system read-only, so as to ensure that this 64K space will not be wasted in the future! Okay, it's over. Your QD driver c should be over 3.4 now! As for the electronic market of memory cards, Zhongguancun has the largest number, and other markets will also have it. The price will not exceed 50, and QD can only be used below1g. Pay attention when buying a card, the card must be thin, if it is thick, there will be a lot of trouble. Hehe, I just disassembled my mobile phone once because the card is thick. I can buy it with your current card, but it can't be thicker than yours! That's it! I used Baidu to give you the answer on QD, so tired! I'll cry if you don't give it to me! Thank you. First of all! If you have other questions, you can ask me. I have been using this mobile phone QD until now, so general problems can be solved! My user name is my qq number. I usually use QD to visit Baidu. I am online 24 hours a day. I can serve you at any time, hehe! Give me points if you feel good!