If you have applied to immigrate to the United States, most likely under either the family-based green card category or the employment-based green card category, you may find that you have to wait several weeks or months to hear back from the office processing your case. Most likely, that is an office of U.S. Citizenship and Immigration Services (USCIS).
Don't panic! Such delays are normal, although certainly bothersome. At least USCIS offers various procedures by which you can check the status of your petition or application.
After you submit a petition or application to USCIS, its practice is to send a receipt, usually within several days or weeks. Look on your receipt for your 13-digit receipt number. The receipt number will begin with three letters to identify the office handling the application, such as EAC, LIN, SRC, or WAC. Your receipt number will be very helpful in tracing your case through the system.
If you do not receive this number after several weeks, make an INFOPASS appointment to visit a USCIS office using the appointment system at www.uscis.gov. When you visit, bring personal identification, copies of your application, and any other materials relating to your case. If you sent the application by a courier service or certified mail, bring the receipt, so that you can show the officer that you really sent it.
To check your immigration status online, you will need a computer and an Internet connection. The USCIS website is at http://www.uscis.gov. Once you are on the USCIS website, click the "Check My Case Status" link and enter your receipt number. It's a good idea to also sign up for case updates from USCIS by creating an account (on the same page).
After you enter your receipt number, you will see seven circles on your screen. The highlighted circle indicates your immigration status.
Another important area of the USCIS website is under the "Check Processing Times" link. There, you can see how long the various USCIS offices or service centers are currently taking to process different types of applications and figure out whether your application has apparently been lost in the shuffle.
If you don't have access to a computer, or have discovered that your case is taking longer than anyone else's, you can make an INFOPASS appointment as described above.
Another option, if your case is at a USCIS service center, is to email the center using one of the address provided on the USCIS website under the "Contact Us" link. Keep your email polite, making sure to include all relevant facts such as the petitioner and beneficiaries' names, the date of filing, whether your filing fee check has been cashed by USCIS, and so forth.
If you're still not getting anywhere, consult an immigration attorney for help.
An experienced U.S. immigration attorney can help you figure out what is happening with your case and will know what sorts of delays in processing are to be expected. In some cases, the attorneys have ways of reaching someone within USCIS that ordinary people don't.