lost all my databases after reinstalling sql server management studio
Background



Q1

Did you reinstall SSMS or your actual database engine? Can you add a picture with what you are seeing?

OP - A1


Q2

Did you use the same login as before? If you reinstalled your database engine the database files might still be there. Can you check your default Data / Log folders to see if there are any database files there? If yes, you could try Attaching these databases again. What does this return? SELECT IS_SRVROLEMEMBER ('sysadmin')

OP - A2


  Yes, I use the same login as I was using before. I pasted "SELECT
  IS_SRVROLEMEMBER ('sysadmin')" and run it on SQL query window and the
  result is " no column name (1) nothing else. I don't know where my
  database was saved to look on it if I can find any thing related to my
  lost database. Could you please tell us where our databases would be
  saved by default in C drive?


Q3£

This means that you are a sysadmin on the instance and that you should be able to see the database if it exists. You can try finding the system databases by using select physical_name from sys.master_files where database_id = 1 and find  the default data path by executing SELECT SERVERPROPERTY('instancedefaultdatapath') AS [DefaultFile]

OP - A3


  Yes, I found two files: LostDatabaseName.mdf and
  LostDatabaseName_log.ldf. Now, how can I move them back to SSMS?




Solution

You can try attaching the database to your new instance.

EXEC sp_attach_db @dbname = N'LostDatabaseName',   
    @filename1 =   
N'C:\FoldersHere\LostDatabaseName.mdf',   
    @filename2 =   
N'C:\FoldersHere\LostDatabaseName_log.ldf';  


An example from Microsoft docs

EXEC sp_attach_db @dbname = N'AdventureWorks2012',   
    @filename1 =   
N'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Data\AdventureWorks2012_Data.mdf',   
    @filename2 =   
N'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Data\AdventureWorks2012_log.ldf'; 


Source

I would also advise to not keep all your database files onC:\ drive. If your drive fills up your server will crash and corruption can occur. It is also important to take backups of your databases, and putting these on separate locations.