Lost all sound. on Dimension 2400

I have lost all sound from my Dimention 2400 running windows XP. As I have had this pc for a long time I deleted what I thought were items I know longer required. I may well have deleted an important file. I have followed all of the items in the support help but cannot identify the problem. I have tried to run the Dell diagnostics but get the following error message when trying to download it.

PLATFORM VERSION INFO

            Windows                                 : 5.1.2600.196608 (Win32NT)

            Common Language Runtime    : 4.0.30319.1022

            System.Deployment.dll                       : 4.0.30319.1 (RTMRel.030319-0100)

            clr.dll                          : 4.0.30319.1022 (RTMGDR.030319-1000)

            dfdll.dll                                   : 4.0.30319.1 (RTMRel.030319-0100)

            dfshim.dll                                : 4.0.31106.0 (Main.031106-0000)

 

SOURCES

            Deployment url                                    : downloads.dell.com/.../DellSystemDetect.application

 

ERROR SUMMARY

            Below is a summary of the errors, details of these errors are listed later in the log.

            * Activation of downloads.dell.com/.../DellSystemDetect.application resulted in exception. Following failure messages were detected:

                        + Exception reading manifest from downloads.dell.com/.../DellSystemDetect.application: the manifest may not be valid or the file could not be opened.

                        + Manifest XML signature is not valid.

                        + SignatureDescription could not be created for the signature algorithm supplied.

 

COMPONENT STORE TRANSACTION FAILURE SUMMARY

            No transaction error was detected.

 

WARNINGS

            There were no warnings during this operation.

 

OPERATION PROGRESS STATUS

            * [22/11/2017 21:40:48] : Activation of downloads.dell.com/.../DellSystemDetect.application has started.

 

ERROR DETAILS

            Following errors were detected during this operation.

            * [22/11/2017 21:40:58] System.Deployment.Application.InvalidDeploymentException (ManifestParse)

                        - Exception reading manifest from downloads.dell.com/.../DellSystemDetect.application: the manifest may not be valid or the file could not be opened.

                        - Source: System.Deployment

                        - Stack trace:

                                    at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri)

                                    at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestDirectBypass(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, SubscriptionState& subState, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformation)

                                    at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestBypass(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, SubscriptionState& subState, IDownloadNotification notification, DownloadOptions options)

                                    at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivation(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl)

                                    at System.Deployment.Application.ApplicationActivator.ActivateDeploymentWorker(Object state)

                        --- Inner Exception ---

                        System.Deployment.Application.InvalidDeploymentException (SignatureValidation)

                        - Manifest XML signature is not valid.

                        - Source: System.Deployment

                        - Stack trace:

Help please from a very old man.