Metric error on OEM 12c/13c - Recollect the metrics from the Target

While working with various targets and OEM, there may be some issues with metric collection. Ti elaborate, let me put one example:
Due to some reason one server got hung and it doesn't allow any connections. At that time your oem will show the old values what are collected earlier. But actually sever is hung state. Then I have rebooted the server. After server came up, still you may observer oem has old metric values. Becuase it has not collected fresh values.

What to do next?

It is advised, in such scenarios, collect the fresh metric collection with reload the agent.

Example:

-- To reload agent
$ emctl reload agent

-- To find help regarding metric collection

 $emctl control agent runCollection -help 
 Oracle Enterprise Manager Cloud Control 13c Release 2 
 Copyright (c) 1996, 2016 Oracle Corporation. All rights reserved. 
 --------------------------------------------------------------- 
 Usage: 
 emctl control agent runCollection TARGETNAME:TARGETTYPE COLLECTIONITEM ... 
 Runs the collections item(s) for the specified target instance 

 Example: 

 $ emctl control agent runCollection example01.xxxx.com:host oracle_si_time_perf 

 emctl control agent runCollection example01.xxxx.com:host oracle_si_time_perf
 Oracle Enterprise Manager Cloud Control 13c Release 2  
 Copyright (c) 1996, 2016 Oracle Corporation.  All rights reserved.
 ---------------------------------------------------------------
 EMD runCollection completed successfully