As you cannot sort messages in your Inbox, it is important to learn how to search for messages, so you can find them quickly and easily.
To search for messages:
Click in the Search box along the top of the Gmail screen
Enter the word or phrase you are looking for
As you type into the Search box, matches will be suggested from Gmail. Click on a result to view that message.
After pressing Return, all matching messages will display. Search chips will also be displayed under the search bar, allowing you to refine the search e.g. to show only messages that have attachments.
Click on a search chip to refine the search, and click on the chip again to remove the filter and show all matches again.
If your search text is matched in any messages in your Bin or Spam folders, a message will display along the bottom of the search results. Click on the View Messages link to view matching messages in your Bin or Spam.
When you enter more than one word into the search box, Google will only find messages that contain all words, as if the word AND was placed between words. You can change this by adding OR between words, in which case Google will return all messages that contain any of the words that you entered.
For example:
Password security would return only messages that contain both password and security, although not necessarily next to each other
"password security" would return only messages that contain both words next to each other in the message i.e. the exact phrase
password OR security would return all messages that contain the word password or the word security
Searching in Gmail is not case sensitive, so the same results would be given for password, Password and PASSWORD.
To show the Search Options pane:
Click on the Search options button at the end of the Search bar along the top of the screen
Fill in all information you wish to search for, then click on the Search button